That's just not how it works. If I was to call a plumber and a sheetwaller, and a painter, I would be paying $6-12k for a leak. This kills any idea of profit for this year.
What really happens is that I put on my big boy pants, I talk to the tenant, I visit the unit, I crawl under the house, I cut out the drywall, I remove and patch the plumbing, I replace the drywall, I mud the wall, and I paint the wall.
I could have it the way you suggest, pay 10% to some property manager and 1500-3000 for any call to any contractor but that means... I'd have to raise the rent, and not by a small amount.
At the end of the day I'm a housing provider, so I'd like to keep rents and vacancies low. This seems to be what tenants want too.
So yes, I'm doing the best I can, but no, my work is not encompassed by a phone call