There's another good reason for working Trad that nobody mentioned-
A lot of people work as window cleaners because it's a nice hassle-free kinda job.
With WFP this is not so!
There are constant problems with WFP, e.g. snagging hosepipes in cluttered gardens, equipment breakdowns, freezing water.. ping around on a weekend changing resin and filters, taking poles apart to clean them etc etc.
In comparison Trad's quite relaxing and enjoyable!
I use both, depending on the job, I do earn a bit more using WFP, but enjoy it more when working Trad.