In the 90's my Dad and us kids would mow 50 old ladies lawns after school as a part time job. We would literally mow and that's it. For whatever reason my dad didn't charge crap so the average lawn was probably 8-10 bucks each. He was probably billing out about $1800 worth of work/month.
I started my business in the spring this year and have 20 clients. I mow, edge, weedeat, blow, spray weeds, spray dandelions, fertilize, aerate etc. I offer more services, and charge at 60/man hour. As a result I bill out around $3300/month.
Offering more services, and not being a low baller means more money per customer.