Depends on the country, airport, airline.

Horrible airlines like ryanair and wizzair id check because they monetize typos (made a typo? Real risk of refused boarding, and changing the name costs money).

I usually fly KLM/AF and I get id checked on less than 5% of the flights I take within the Schengen zone.

Ryanair's passport policy predates Schengen and is largely driven by Ireland's aviation rules on pax ID, not any Revenue-driven measure.