when I applied for a tourist E-visa from Spain last year I actually had to submit my empadronamiento (adres registration) as proof of address. A visa stamp wouldn’t have been enough (I’m a EU citizen so wouldn’t have one anyways). If they want a similar type of document once they implement the E-visa system in neighboring countries I wouldn’t be surprised this will also be implemented like this there.
Yh that don’t really work if you have residency somewhere in Europe and you go to a country like Laos or Cambodia and have to prove residency there. For example my case I would have to fly all the way to Spain. Buy tickets and find accommodation there and then apply. Costly, better just walk in somewhere.