I have seen no overall increase in the number of non payers, I have a couple more now than I did 10 years ago but then I am selling ten times the number of items.

You can block all bidders who have more than one unpaid item strike in the last 12 months, this takes care of the serial offenders.

For the others don't let them get you down, just open the unpaid item dispute after 4 days, the vast majority will pay then and for the odd one that doesn't you close 4 days later and relist or second chance.

If I have one that hasn't paid by day 6 and there are underbidders I will sometimes email them and say it looks as if the buyer may not pay and it will possibly available for a SCO in a couple of days.