[Kirby64]

Nobody would attach the timer to the actual moving drum, so the worst it has to deal with is physical vibrations from use (which, admittedly, can be quite violent if you have an unbalanced load). There are very few digital circuits that are actually meaningfully sensitive to vibrations. At worst, it's a manufacturing problem to make sure the PCB/solder joints don't crack from vibration.

In comparison, the mechanical timer is physically moving. A clockspring, or some sort of mechanism that physically sets the time remaining. Depending on how it's built, vibrations are a harder problem to solve. Not impossible, obviously, but it certainly adds cost.

Also, for most appliances we deal with today... they usually ARE simple to work on. Simple switches and mechanical contrivances. Parts are typically readily available... even PCBs, although possibly not at great pricing. There's certain appliances where you are basically screwed (fridges come to mind...), but that is mainly in my view because the typical failing part is the compressor. Nobody is rebuilding a compressor themselves.

[willyt]

In a fridge the typical failing part is the plastic shelves in the door. The compressor almost never fails and discarded fridges are a great source of cheap pumps if you need to scavenge them.

Source: The episode of 'The Secret Life of Machines' on fridges. Search it on YouTube.

[Kirby64]

Maybe for certain models. Personally I've never had a shelf break on any fridge I've used, which makes it sound like that's a user error to me.

On the compressors, there was a vast swath of Samsung and LG fridges that had known defects on compressors causing them to fail. Right now, the ice machines are probably most problematic. If you own a Samsung fridge with an ice maker you know what I mean.

[EdwardDiego]

On the Samsung fridge aspect...

A few years ago I was renting a house that came with a Samsung fridge that provided chilled water / ice. My kids loved the chilled water.

However, our usage of it caused the paint to start bubbling below the dispenser, and the owners of the rental wanted me to replace the door at a cost of ~$800 USD(!).

I argued that we were using the fridge as designed, so we weren't liable, instead they should discuss what looked to me like an obvious design flaw with Samsung.

They disagreed, so we ended up in court. My defence was about 12 pages printed from an appliance review site of people specifically complaining about this paint bubbling.

Easiest win ever, but seriously, how do you put a device that works with water into a fridge and fail to ensure it can't leak under the paintwork?