Why did I have to undergo a MOT at the workshop because of a serious defect?

I did not receive a TÃœV sticker due to porous, torn rubbers in the wishbone bushing. When replacing the wishbones and shock absorbers, the track needed to be readjusted. I ordered a suspension kit (wishbones, shock absorbers, ball joints, and tie rod). We hobby mechanics installed the parts (wishbones, shock absorbers, and ball joints). The…