Mechanics do these things because they think it may make it easier for them to do another job near,around or on it.
Not MINI related, but back in the 70's my dad used to take his car into a Rootes dealers for service. when it came back it ran all jerky and juddered and pinked, upon checking we found the timing was way out so reset it and all was well, until the next time it went in, same again. My dad complained to the service manager who said they had not touched the timing and it must have been out when it came in for service.
So next time I marked the distributor position with a scratch, and sure enough when the car came back the timing had been altered.
Armed with this we took the car back and an investigation ensued, in the end it was found that the young lad putting new contact breakers in the distributor had a good idea to save him bending over in the bowls of the engine compartment he removed the distributor and took it to the bench to work on, when he refitted it he didnt realise it had to go back in the same position and just dropped it in and tightened it down, hence the timing was out. once pointed out my dad got a free next service.
So just because in theory theres no need to move something they just might in their thinking it will make it easier to work on.