Both their functionings are complex, so people can get impressed. But for both of them, all the complexity is inside the device and there isn’t much to put together; and the way they hook up to your house is really simple.
Why YSK: so you don’t live too long with a broken toilet or garbage disposal, thinking it will be too hard to replace. Those two are some of the simplest things to DIY.
In fairness, the hard part of replacing a toilet isn’t the replacing of it, it’s moving it about, and having to deal with the mess.
A plumber is usually better equipped for that, and would know what to expect, whereas someone who is less experienced might end up destroying the toilet and/or splashing water everywhere (if they have a siphonic toilet), or breaking something else.
A tap is probably easier to replace, by comparison.
In theory a tap is easier to replace, every time I’ve gone to replace a faucet I’ll be damned if I didn’t spend at least twice as long as I thought I would contorted under the sink at an odd angle muttering curses to myself.
Big game changer for me with faucets was when it dawned on me that those shitty plastic nuts that like 90% of all faucets are held on by that are next to impossible to get a good grip on are like $2 a pop and the new faucet probably came with new ones anyway, so why the hell do I care about getting them off in one piece? I just take a chisel to them now.
Replaced a garbage disposal recently and it was pretty damn painless, I could get at everything pretty well from a comfortable seated position on the floor outside of the sink, no need to crawl under there or grope around blindly. The old one actually went on me about an hour before I was hosting a party. I was expecting it to be a pain in the ass, my usual DIY buddy was at my party and I gave him a heads-up that I might be hitting him up the next day if I needed a hand. After everyone left at the end of the night I watched a couple of YouTube videos, then pulled out the old garbage disposal, took me maybe about 20 minutes. Went to bed, woke up and ran to the hardware store the next morning and had themnew one installed by noon and didn’t need to hit up my friend for her. Probably would have had it installed by about 10 or 11 but my disposal is hard-wired and I needed to run out for a cable connector because the new one didn’t come with one (would have reused themone from the old one, but it didn’t have the nut, the old disposal was actually threaded for the cable connector and the new one wasn’t.
I haven’t replaced a whole toilet yet (although I’ve taken them apart and replaced all of the internals and installed bidets) but really you just turn off and disconnect the water, undo a couple bolts, and then you pretty much just pick them up. They’re a bit heavy and awkward, but there’s not much to it otherwise, it almost seems like it’s too simple to actually work but it does.