https://ubuntu.com/blog/chromium-in-ubuntu-deb-to-snap-trans...
Canonical couldn't afford the maintenance costs for it. On Ubuntu distributions it's either the snap or you have to create some weird frankendeb aspect by pulling from Debian.
They explained it better than I would.
In other cases, I don't think of a case where apt installs snaps over apt. I think the only priority for the decision choice was based on most recent version. Although this aspect I am slightly unclear.