>Also, Americans move around too much to get an invitation. Sheesh, half the time my mail can't find me.

Ads always find you. What's cheaper in the total: that the state subscribes to the same USPS update service (and imagine, that'd be state paying the Feds for a service) as any other business with subscribers does, so when you move they get an update within a month or two, or that everyone needs to take a ride to DMV or equivalent, engage a clerk in a friendly conversation for a while and get to generally do even more paperwork than really necessary when moving?

> The government or electoral bodies would need to know where I am at all times in order to send me an invitation.

Not at all times, only a few weeks before the elections. I've moved three times here, and the advertisements to my name followed within weeks. So... you may get skipped if there are elections in the weeks immediately after you've just moved in, but that'd be it. Next time you'd get an invitation.

> They only know my address is I submit it in order to update my voter registration after a move. Registering to vote is not a requirement that is enforced on us. It is considered a priviledge and not mandatory.

There was one theatrical troop in Belgrade, who actually operated on the radio ("Indeksovo radio pozorište" - "Index's radio theater" on Belgrade 202, index is a college student's ID with attendance and exam record in it, and "Index" was a daily hourly show for university; these guys had Sundays). Over the years they had many many good ones, and you just reminded me of them: "We have nothing against privileges, as long as everyone can benefit from them".

Invitation is not a sub poena. It's just an invitation - the turnout is also around 50% in Serbia :).