"Borders: Doesn't this have something to do with the
Schwengen zone? Once you're in the zone, travel between
countries is easier. Yes, we should have something
like that with Canada."

Yes, of course. During normal times, there are no more border controls.
If necessary, they can be temporarily re-instated. This sometims happens,
not only to catch criminals, but also to stop hooligans from travelling
to a football game. But it's not such a big deal, since in Germany (and
probably in most countries in Europe) everyone has to carry a photo-ID at
all times and the police can always ask you to identify yourself. Strange
that this causes such a big problem in other countries. I recently saw
a map of the world with different colours with regard to how much government
surveillance there is. The US was at the top of the list, Germany somewhere
in the middle. (There is a lot of vocal opposition to increasing surveillance,
but this is basically a loud minority; most folks don't have a problem with it.)
Scandinavia etc was pretty high up on the list. There, the degree to which
personal data are publicly available is quite large. (OK, this is different
from government surveillance, but if the data are publicly available, then
they are also available to the government.) When Sweden joined the EU, there
was an extra agreement that this could be kept. Just to give you a taste: anyone
can see the earnings of and taxes paid by anyone else, no justification necessary.

"Taking the side-roads when the Autobahn in Austria wants to go through a 20km tunnel. What views! Some of the tunnels don’t seem to bypass anything, they must be there to keep snow off the roads and highway noise away from the rural settings. Pretty expensive way to do that, though."

I'm confused about this remark. Most tunnels exist because they go through mountains.

"In particular, over $7 for gasoline, and they take it in stride. They use a lot more transit all over Europe of course, and drive a lot more tiny cars that are much better on fuel. I rented a Toyota Yaris, which actually was quite suitable except climbing some hills in the Alps. They need to start selling more cars like it in the USA, if just for parking."

Not a problem when you don't have to pay for the education of you children, including
college, out of your own pocket. (Of course, you do indirectly through taxes, but
people with more children aren't punished and the amount pays goes according to your
income, so of course it is redistribution of wealth but it is a good thing.) Exchange
rates are noticeable, but completely uninteresting to the folks who live there. Some
things are more expensive, some cheaper. The only real way to compare is to see what
standard of living you would have in each country, with the income you would have if
living there. Even this is different for different folks, depending on what they
spend their money on.

"Most of the old towns had complex regulations about who could drive in and when. As such, it could not be expressed in international road signs, making it very confusing for tourists — and these old towns are the main tourist targets — who come in cars. Bring a good translation guide to try to understand where you can stop or park! I’m not demanding everybody speak English, of course, but in tourist areas a special effort is worthwhile."

This might be intentional. Basically, even for people familiar with the territory, there is simply
no reason to drive a car within a historic town. If you are travelling by car, park outside and
take the bus into town. Inviting more cars from tourists wouldn't be a good idea.

"Germans for some time have been huge consumers of bottled mineral water, usually fizzy. I don’t like this myself, and in fact I don’t even like the bottled still waters which are the only alternatives a lot of the time. It’s not just the fact that it’s $8 for a bottle at most restaurants: bottled water is very un-green which you would think the birthplace of the Green party would understand. But when I asked for tap water they always looked at me strangely, and in one case even refused to serve it to me! Attempts to explain the ecological point always resulted in “that’s the first time I’ve heard that."

Tap water might be greener, but I doubt that bottled water is worse than other bottled drinks
(which are mostly water). Not all fizzy water comes out of the ground that way; a lot is
carbonated after the fact. I think it has more to do with taste (fizzy water, that is). One can
buy machines to carbonate tap water at home. There are probably a few people who drink it because
they think it is healthier, but the trace minerals aren't enough to matter and actually the regulations
concerning impurities etc are stricter for tap water than for bottled water.

Yes, drinks are expensive, but it's a different model. In many restaurants in the States, drinks are free.
Here, for many restaurants food is a zero-sum game and profit is made only on drinks.

"Like many other countries, a hotel room for 2 is much more than a room for 1. Which is, I guess, good for the single traveller and bad for the couple. Of course, one main reason is that almost always a room comes with a fairly nice breakfast. Some hotels list their double price, some list a per-person price for a double making it harder to compare."

Considering the size of Germany, very few Germans stay in hotels while travelling privately. Most
guests are probably business folks whose company pays the bill. So, prices probably aren't as competitive.
Some have a price per room, regardless of how many people are in it, and breakfast is extra (per person,
of course). Double beds exist, but are a bit rarer.