Why are entry-level CNC mills cheaper than entry-level manual mini mills?

Making a machine CNC ready has a neglible cost. Electronics cost nearly nothing, and are easy to do when your not aiming to super quality. All of the moving elements can be simplified because you dont need to present user interface through mechanical couplings and dont need to worry about user safety.

So a bit counter intuitively cnc machine can be simpler than a equivalent manual machine. Now that is to say the CNC does not even need to be equivalent to a manual machine. It can also be made for much lighter loads than a manual machine would, since there is a limit on how slow a human can be expected to go. So a cnc that just takes really slow passes on a PCB does not need to be much suturdier than a 3D printer.

Then theres the economics. A super cheap and light CNC is actually semi useful as one operator can batch many machines. Whereas a manual is still limited by the cost of a operator so it does not make sense to invest less into that use. But again this depends on market, CNC is obviously good for production runs. But not necceserily for very small scale or toolroom, modelmaking (die) or prototype work where a manual tool is still invaluable. Especially when paired with a CNC or two.