For better or worse, elections in the USA and most places have people who are classed as official candidates. There is a bar to pass to get that status, even if write-in votes are allowed, which they are not always. There are even in many places official parties which are different from smaller parties.

So yes, that's a difference. You have to get lots of signatures on a form, file the right papers etc. That's enough to keep the spammers out.

Note that this plan does not necessarily stick anybody with a tab, if it uses unsold inventory. It may for a short time diminish the donation of unsold inventory to tax exempt charities. Pretty small price to pay for fixing one of the system's grandest flaws.