[munk-a]

I don't know about painter/carpenter/landscaper, but if you want to talk about plumber, they will be paid for every minute on site, their commute and usually their advertised "minimum visit time" if the job is particularly short.

When you are informally on-call you are unable to enjoy your time to the fullest, your employer is demanding a price from you without compensating you for your time, it is an obligation of yours for yourself, your friends and family and your co-workers to demand fair compensation for this time - that's a key component of labour exchange in the free market and good unions exist to help protect those rights for junior employees who tend to have less leverage when negotiating their rights than more senior folks.