A lot of things are simply too expensive to fix. Dish Washer was acting up, GUESSING at what was wrong with it...you could put 100-200 bucks into it and MAYBE fix it. But it will probably break another part or have another issue in another year or two and cost more to fix.
Even a lot of the "professionals" guess and go for the most likely repairs........even on cars.
Phones/tablets/etc....assuming you can get the device open without breaking the little plastic clips. A lot of MFGs glue stuff down and make it a real pain to attempt repairs, and require soldering in the case of batteries often times.
My parents have a almost 30 YO fridge of my grandmothers......that works fine. Doesn't have any bells and whistles like most fridges they sell now, but it still works. In the meantime, they've had one fridge die after 10-12 years and the replacement had poor design issues within months of purchase that last to this day. You could keep fixing it, but it'll just keep breaking because it's a dumb design. The ice making pushes the ice up hill, and the ice binds and causes the pieces in the mechanisms to strip and break. To give the freezer an extra little bit of room. You'd think companies making fridges and appliances for going on 40-50 years might have a little inkling of what might be a design issue by now.
Oh and microwaves, those bastards seem to be a crap shoot at this point. Got the grandmothers ancient microwave, new ones might last 2-5 years before something important in em dies....and they can be rather dangerous to futz with to save 100-200 bucks.