I recently replaced a dishwasher, and while the old one just had a cable to plug in, the new one needed some power box, so I had to mount that, and the existing holes for cables and hoses weren't big enough, so I needed to enlarge those. Not a big problem for me, I'm handy, but a lot of people aren't comfortable making holes in things. Physically moving the machines wasn't that hard, but I have plenty of dollies and what not.

I was lucky and someone was interested in the old one to try to fix it, or to swap parts and make their current one look nicer, so I didn't have to haul the other one away to the dump, but that's something the installer will typically do.