I assume collections pays (pennies on the dollar, but still >0) for each case, so being more thorough in verification of this literally costs them (the ISP) mon

I assume collections pays (pennies on the dollar, but still >0) for each case, so being more thorough in verification of this literally costs them (the ISP) money. And, also, people who are being pissed off aren't clients anymore anyway. So of course they'd not do it.