youwantsome - Many stories here are from single people, many self employed. Quite different to yours it appears. You don't seem to have read or understood the posts properly....or want to....
In most cases mentioned it is an 'Accusation'. The use of the word 'may' is used legally all the time to avoid being prosecuted just in case information is wrong. This accusation is designed to scare and panic people into to providing the volumes of information requested and ignore their rights (not just a few payslips). Most of the details they want know were never requested at the time of application (your short list doesn't even resemble anything like what they want). A lot is irrelevant and would prove nothing.
Perhaps you wouldn't be upset if your husband had been tragically killed (and HMRC new about it) and then he was named in your letter and you were asked to prove he wasn't living with you by producing a year's worth of bank statements, mortgage documents, credit cards statements, utility bills, etc, etc, etc the list goes on......Or the person you has to seek out their abusive husband who has not seen his children in year's in order to get evidence from him of where he is living.
Why are people being asked for evidence of child maintenance payments when it doesn't count towards Tax credits?...and why should anyone, just because their address has been associated with another name, who could be a neighbour, be asked for this level of information? There are much simpler, reasonable and more cost effective ways of resolving these queries and which would be less distressing.
No-one is questioning the right to check the entitlement to benefits...it is public money....This is not what has been said at all.
Yes this is an Invasion of Privacy and its purpose is questionable, as is the company undertaking the work. You can ask HMRC is they are legit and they will say yes....ask them a few more probing questions, even to their management - they haven't got a clue.
Your analogy with the builder is not even worth going into as it is nothing at all like this situation.
You seem to be saying that everyone commenting here is actually guilty and living the person named or unnamed in the letter, by your last statement. Most people here haven't "changed what they originally told them without informing them". To use your words - I'm 'damn sure' I have the right to query it!
People join forums, to share, get support and advice and expect some respect as all are individuals with different needs. Others need to get their Saturday night kicks...