It all depends on how the proceeds are divied up. To me, the numbers don't sound right for a few reasons-
1) No way a proprietor rents out a barber chair for $150-$200 a week and watches his employee rake in $500-$800 juevos during the same period without getting a cut of that. That's not the way Dominican business owners roll.
2) From what I know, barbers DO pay weekly rent for the chair, but customers pay at the counter and the barbers get a percentage for each customer. The tips are where they make their real money.
3) Barber shops usually charge minimum $15 for a cut, with anything else extra. It's not $10, unless it's one of those places that have trainees working the scissors, and I only know of two places like that in NYC, both close to Astor Place Haircutters. And it's not $20 because that's too much. Salons that cut women's hair charge more per customer because they do more stuff for each individual client.
As for the other points made in this thread-
1) Parking attendants make crap money, and hardly any of them have benefits. That is why you only see immigrants doing that type of job.
2) NYC doorman never have and never will make 150k a year. Maybe 40-45K. The management companies that are in charge of maintaining these buildings are in the process of restructuring their employee pay packets, and unless you are working a swanky building with a lot of tenants, tenants who like you, you'll get your Christmas bonus alright, but the weekly salary is going DOWN, not up.