"It would just be a hassle to migrate."
If only DB clients all used a common language to talk to the server. Something with a proper standard behind it, ideally established years ago so that everyone had correct implementations by now.
(Edit: Yes it can't be *that* simple or else there wouldn't be so many people apparently stuck on the most expensive provider, but speaking as someone with no DB background it does appear odd. On paper, changing your DBMS should be no harder than changing your browser or compiler.)