Az, these vary from large compagnies like NetJets Europe with hundreds of pilots and schedules to single pilot operators where the one employee is the Jack of all trades: pilot, maintenance planner, hangar keeper and whatever else the owner comes up with.
Flying a single engine anything will never offer the same salary or benefits as flying for an airline.
A lot of smaller operators have gentleman’s agreements, a pilot leaves and they bring in their own replacement. Many of those jobs will therefore never be advertised.
Many of those jobs are essentially part time as the airplane is only used by the owner.
Part time jobs come with part time pay unless you’re very very lucky.
Keep in mind that these jobs generally don’t offer that much flying, maybe a couple of hundred hours a year. This may not be enough to move on or upgrade in a reasonable time.
I used to know an individual who was silver spooned into a large business jet right after his CPL, 5 years later he was complaining he couldn’t move on as he was still well under 1500 hrs for the ATPL, as a matter of fact he was still under a 1000. His first job turned into a golden cage. Not enough flying to stay not enough experience to go.
Life is different when you’re 21, when you’re 31
you need your first (and second and third) job to get you lots of hours in a relatively short time to get you where you need to be instead of having your career stall out.