I know of one long standing cleaner that rings up the night before, and his customers leave the money or cheque in a pre arranged hiding place. It works for him, but I doubt if it would work with some of my lot.
The last two days I have been working on a marina complex, mostly holiday homes, never a problem with these, they either send a cheque or pay online.
I do other areas where many don't even have a cheque book, so no point in leaving an envelope for them.
You have to adapt to your customers, I have lost many a job because I didn't collect and the bill mounted up.
I guess that most of us have some customers who we never worry about, we know they always pay,
with others you have to be more careful, and for these collecting is the only way.