Ethnicities aka Stop Spawning Judith Ward in Mt Komorebi

Absolutely agree. I also think that homeless sims should have some way of being assigned to a world so that they only spawn there

If you use mods:
https://lotharihoe.tumblr.com/post/622921247655919616/sso-sim-spawn-overhaul-download-google-drive

This mod won't stop out of world spawning COMPLETELY (except for walkbys on residential lots and a select few venue types), but it will make it so the game prefers sims from that world so that you see them more often. It can get a little... empty when you're in a super small world but it helps.