Wouldn't you? Whilst employed by the Civil Service I owned a two branch accountancy practice years ago.
My two daughters' ran the practice with two other employees for me whilst I was a consultant and principal. I would not have trusted anyone outside the family to do that for me.
You seem to have had a charmed life dodging round the rules.
I was not allowed, by the Civil Service, to undertake any activity that could be seen as a conflict with my Civil Service duties.
Therefore I most certainly would not have been allowed to have any involvement whatsoever with the private investigation industry, so IMO you were lucky, as an HMRC Officer, to be allowed to be involved with the accountancy industry.
Of course the systems are to be used provided that what people do is legal and above board.
It's nothing different than playing the rail ticket scam. It can be far cheaper to buy 2/3 tickets for a section of travel rather than buy one ticket for the whole journey.
I'm just about to set off on a bus to the large town using my bus pass. I could just as easily use the car and park up anywhere on double yellow lines with my Blue Badge. I save on fuel costs and cost the County Council the cost of the bus travel.
If the system allows itself to be abused in these ways then why not abuse it - it's perfectly legal.
Well by using you logic it could be said it's a scam buying a 2nd class rail ticket instead of a 1st class ticket.
The system operates purely because the majority of people don't abuse it.
If we all followed you the system would be bust.