I've had a few businesses - Valeting, Handyman, courier owner driver. I've just moved into window cleaning and can honestly say it beats the others hands down.
Valeting - almost everyone wants it about 50% cheaper, it's hard to get repeat/regular custom, so you're stuck to a lot of one off unpredictable work, and 30 minutes of rain can cancel a 3 hour £60 job. It's dirty work, insurances are more expensive and more things I could mention.....
Handyman - you get a lot of people expecting a weeks work at the price of 2, and again regular custom is rare as most are one off tasks/repairs etc. So the wage is unpredictable.
Courier owner driver - wages have been driven so low that a full weeks work will earn minimum wage, without accounting for the mileage and depreciation of the van.
I know window cleaning has it's downsides, like a lot of things, but common sense sees you through most of it.
Few of us take time to remember how lucky we are. Imagine working 12 hour shifts in a dark warehouse with a few 10 minute breaks and a set 30 minute dinner....