> Just as example - how do you create read-only user (SELECT only) in Postgres? In MySQL it's extremely simple and it works, while in Postgres it's a nightmare to create

Isn’t that

  GRANT SELECT ON ALL TABLES IN SCHEMA foo TO bar;

?

> and maintain

If you mean you want to grant a user select rights to whatever table gets created in the future (a somewhat questionable idea from a security viewpoint):

  ALTER DEFAULT PRIVILEGES IN SCHEMA foo GRANT SELECT ON TABLES TO bar;

I think both are possible in PostgreSQL 9 and later (https://www.postgresql.org/docs/9.0/sql-grant.html , https://www.postgresql.org/docs/9.0/sql-alterdefaultprivileg...)

That version is from 2010.

I guess the lesson is that both these systems evolve fairly rapidly. You can’t use quirks you remember from over 5 years ago to judge their current versions.