The problem isn't that they're asking for payments, it's that they're demanding payments when they don't actually have any evidence that any are due, which is why they simply disappear when
asked for any evidence, for a while anyway.
The problem is 1) when people act in good faith and assume the debt is actually real and just pay, 2) people who might be afraid that things escalate and pay to "avoid trouble", and 3) the fear that it might negatively affect your credit score. The power imbalance is very real.
When a debt collecting agency sends you a bill, this is essentially it's an accusation that you didn't fulfil your responsibilities and duties. I don't know about you, but I tend to make pretty darn sure that I'm right when I accuse of someone, especially if it's a very specific accusation.
While mistakes can surely be made with the best of efforts, it's the debt collector's responsibility to correct any, rather than just shrug and ignore any rebuttals.
Of course, that's not in their financial interests (quite a few debt collecting agencies "buy" outstanding bills and try to make a profit from collecting them).
It's not my responsibility to prove I don't need to pay something; the burden of proof is completely reversed; eBay has been harassing me for years for an £18 alleged "debt" where I have already explained in great detail and with great patience why it's erroneous, but they don't listen: they simply don't reply and then send a new message as if I'm talking to a wall. I had to block a whole bunch of email addresses and phone numbers, instead.
> The alternative is magistrates and lawsuits.
"Oops, sorry, looks like I don't actually have a bill from AT&T which says you owe anything!"