Engines are much easier to work on when they aren't in a car. It's when you have to work on them in the car (especially modern cars) that it gets tricky - or sometimes impossible (there are cars where certain parts on the engine are virtually impossible to remove, because the engine was assembled and installed before the body was fitted over things - usually, the only way to fix these is either to remove the body (virtually impossible for the diy'er), or by tearing half the car apart just to get to the part (and praying you can get it all back together afterward - without any extra parts left over!)...

True, though this cuts both ways: a similar teardown of the motive system of a Tesla would be like 8 or 9 seconds. Some fixed magnets, wire, a single speed gearbox, that's it.

Internal combustion engines may be designed for maintainability, but they have a much harder problem to solve to actually achieve successful maintenance.

Yet, my ICE is cheaper to repair than an out of warrany tesla.