Earlier quoted context omitted.
Every time I see a job post mentioning mysql I realize they just haven't discovered postgres, or they have some really gross problem. :/
Or they want to allow for case-insensitivity of some data, like for example email addresses on login forms. As much as postgres is overall better than MySQL in so many ways, it's still ridiculously difficult to set things up such that SELECT id FROM users WHERE email='foo@example.com' returns the same result as SELECT id FROM users WHERE email='Foo@example.com'
Here's an example of doing that in PostgreSQL:
create table user_email (
email text not null
);
-- create a index on the lowercase form
-- of the email
create unique index user_email_case_idx
on user_email (lower(email));
-- select using the index, with the lowercase form.
select 1
from user_email
where lower(email)=lower('Foo@foo.com');