Because you should focus on what makes you more money: chasing a one-off debt or chasing good, new, repeat business.
"Principles" should not obviate the need for good, cold mathematical calculation of effort versus return before embarking on action.
Vin
If you organise collections properly it should not get in the way of growing your business. I generally collect one evening a week and an hour on a Sunday, this in general covers everyone. If I can't catch someone in when i'm next in the area a simple text or phone call to leave the money under the mat/plant pot etc generally suffices. Not saying I haven't had bad payers and messers, I let those go, but it doesn't stop me collecting what's owed.
I have been window cleaning since 1986 on and off, worked in general this way and do not have one person from all those years owe me money, apart from a £14 job from 3 weeks ago due to her working away.
If you are willing to clean and not put systems in place to collect the money owed then you have your priorities wrong as we are in it for the money not the clean ... I am not talking of you personally but cleaners in general.
I really cannot understand why someone would spend half hour or so on a job and let that money go, but each to their own.