Why do apartments not allow people to work on cars?

I actually own a few apartments. But I read recently that people basically expect not to be able to work on their cars… Which I found a bit perplexing.
Gawd knows how ridiculously expensive it is to take a car to the shop…
Added (1). uh. Yeah I do own 3 apartments. The parking area is wood chip. Concrete I could see not wanting oil stains on, and asphalt the same to a much lesser degree.
A tenant has worked on his corvette. Noise problems are noise problems, whether they're from cars or parties or whatever, so I figured noise issues could be handled via the normal reasons.
Heavy parts? Like exhausts? Alternators? Usually people don't want to drop their auto parts onto the ground, so it couldn't be terribly common.
Added (2). Nico - thank you. And Anonimiti - you too. Thank you. (I'm not much of an appreciator of aesthetics)

I suppose that's a possibility with most apartment complexes having cars parked so closely to each other. Personally, my parking areas are a) ample, and b) completely separate areas for each unit, so I didn't immediately think of potential damage to other tenants' cars

kj566- you're wrong
equality7…- you're wrong about my not owning apartments (no mortgage, either, btw)

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