In the end cars are luck of the draw; FSH is a very, very narrow band. I happened to be in a small garage 7/8 years ago and watched as the owner/mechanic filled an E90 320d with 10w40 semi-synth. So FSH but a ticking time bomb of a turbo. And if it went bang 18 months later the owner would just write it off as one of those things. Bad luck and all that but they'd never think they hadn't been doing the right thing.
In fact, over the years I've concluded that one of the worst things that can happen to cars is to take it to a garage. Garage mechanic isn't a particularly high end job most of the time (and I've got friends who are mechs.) They're not paid well, in the larger garages they have a stupid schedule so everything is rushed and, frankly, many don't know much about anything automobile related. In other words, cars survive despite garages, rather than because of them.
I reckon most main dealers do try and do a good job. My mother has a 35,000 mile 53 plate Fiesta with FMDSH. It's in really excellent condition (partly because it lives in the garage) but it's still worth buttons despite having spent thousands in servicing to get redundant replacement cambelts. In fact, the one thing that makes it even more worthless is that because of the lie of the one lady owner, the clutch feels paper thin (steep driveway to negotiate!)
And that's another thing. Servicing only really keeps on top of the engine innards. So many other parts of a car will just fail apropos of nothing. The MoT keeps an eye on important ones and no amount of servicing will stop an alternator randomly throwing in the towel. If anything owning cars is nothing more than a game of pass the parcel where you can hear it ticking.
Has a car had oil changes? Yes. Fine. Hopefully it was the right oil. Beyond that; pfft, buy on condition and sacrifice a goat.
