Countertop dishwashers exist, they're great! Just got to run a hose for water and either hook up the drainage to your U-Bend or dangle it into the sink. Ezpz! :-D

Where do you live that they don't?

Here nearly every single apartment comes with a dishwasher. About the only ones that don't are student apartments or maaybe the cheapest ones, but even then when I was looking for an apartment pretty much all of them had one

Countertop ones exist

Yes they do. I have a dish washer in my apartment. I think most do here. And there's countertop ones. Had one for years, worked great!