UK law and US law works quite differently. Copyright infringement claims under 10,000 GBP are handled by the IPEC small claims track. Legal Costs are not covered in the small claims track ( unless the claimant or defendant behaves unreasonably) Thus a defendant will have to pay damages for the infringement plus a few hundred pounds court fees. Typical damages awards are in the range of 1000 to 3000 GBP. I am not convinced that people will sell their car, move house, close their bank account , close all their social media accounts, go ex directory and hide for 6 years rather than pay a couple of grand.
Also if they do play that game, they are also playing a game of double or quits because if they let court judgement go to collection by High Court Enforcement Officers then the judgement debt will likely double.
I have known of a few cases which have gone to collection and its hard to know what the defendants were thinking but I think its most likely that rather than deliberately hiding from a debt , they have gained the false impression from here that the claim and the legal process is not real but a scam and therefore they do nothing until an HCEO turns up and says "right then, Im taking your car".
As for the contents of claimants letters, how both claimants and defendants behave in their correspondence is set out in the Civil Procedure Rules. Claimants are expected to set out the legal basis for their claim, how it is calculated and the consequences of not settling out of court. If the claim letters contain undue threats or other unreasonable behaviour then the courts will likely award a much lower level of damages. Statements along the lines of pay me or I will issue legal proceedings are not unreasonable and indeed the claimant is expected to set out the consequences of not reaching a settlement.
Similarly if defendants misbehave the likely outcome will be additional damages for the claimant. Of particular note is that ignoring the claim , the usual advice here, is and has been held to be unreasonable and the court can , will and does award extra damages pursuant CPR 27.14,2(g). I know of one claimant, a photographer, who was awarded over 750 GBP under this head alone because the defendant failed to fully engage with the claimant. That was in addition to the damages and came to a total of over 2800 GBP for the copyright infringement of a single photograph.
My own advice to anyone receiving a copyright infringement claim is the same as for any other legal claim , ie first check that the claim is genuine and if it is then try to reach an out of court settlement. Knowledge of IP law and IP case law would likely help in reaching an advantageous settlement. My view is ignoring a lawful claim is most unwise. It only works if the claimant gives up. If he or she does issue a claim then ignoring it will likely prove a very expensive mistake, costing the defendant many times what they could have settled for.
Jaw Jaw is better than War War !