Capstan could have been fitted by the dealer before the regs came
Sure, could well be, as could other types of winch, as could "roo bars" etc etc.
If there are sharp edges the plod are normally a bit more inclined to get bothered.
I once bought an old style Mini, that had no front bumper, drove it home then the plod who had been following me stopped to have "a word". They told me I had driven all the way with my reversing lights on!
Sho nuff they were, (obvs aftermarket) we all had fun trying to make them come on again and couldn't!
They also pointed out the cutting edge on the front, suggested I got a length of garden hose, split it and put it over it.
I then pointed to the other old mini on bricks, on my parents' parking area, and told them I'd be swopping a lot of stuff over onto it!
They then just laughed and wished me luck with finding the switch or whatever for the reversing lights. and left!
Plod could be decent back in the day, they accepted without question that I had just bought it.