My car passed the driving test but failed a real inspection

I'm still shocked. I just bought a used car that drove perfectly and passed its mandatory test, so I thought it was in great shape. A friend who knows more about cars than me suggested I take it for a proper professional inspection at a place he trusted. They found issues I never could have imagined, worn suspension bushings, a very slow coolant leak, and an engine mount that was starting to go. He sent me a link to an article at khaleejtip.com/hidden-car-problems-inspection that explains exactly how these things stay hidden. It was a wake up call. Now I'm glad I caught them early, but it makes me wonder how many cars on the road have hidden problems. Has anyone else had a similar experience where a car seemed perfect but needed major unseen work?