Aircraft get a lot of mechanical attention
No pilot wants to fly an unsafe aircraft, and we sure don’t want them possibly crashing down on us. So, the FAA and other international organizations require very strict attention to aircraft maintenance. From time to time the FAA issues directives for specific aircraft that have a safety issue. Professional pilots take aircraft condition very serioiusly, and they inspect the plane every time they fly it.
It takes a lot of study to become an aircraft mechanic ( A & P certificate = Airframe and Powerplant ). After you get a certificate, one still needs experience, and there are a LOT of different kinds of planes, plus many of the same model use different engines or have other variations.
Vintage aircraft are a whole other story. Parts may be very rare, or not available at all so they must be custom machined. In spite of those challenges, many antique aircraft are still flying today. There is a precision in aircraft that is unlike most manufactured products. Basically, an aircraft must have everything it needs, and nothing it doesn’t need to do its job.