There are plenty of machines for which the manufacturer cheaped out on buttons and displays, so instead you press a complicated sequence of buttons that is poorly described in the manual. And a machines, especially drip machines, are not easy to safely rinse, so getting the cleaner back out can be extremely challenging.

You can't cheap out on a coffee machine. That's basically the one rule if you really like coffee (and health for that matter)

Source: I repaired coffee machines for a while as teenager and seen horrible mold or quality machines. Nothing in between

I’ve encountered cheap drip machines, and I’ve encountered pricier drip machines. I have never encountered one that didn’t have an utterly terrible path for the water.

And even some rather nice Breville espresso machines have something like three buttons and a couple little LEDs. They work well, but good luck deciding the blink pattern meaning “you must descale me now” and actually running the descaling cycle without a manual.

I was always particularly concerned about that tube where the heated water goes from the bottom to the top and pours into the coffee filter. It's so thin, I could never believe it could be cleaned from whatever buildup is inside it.