You know why automatics are sealed these days? They don't expect them to need service. Here in the U. S., I actually had to call around to find someone that would do a clutch. When I was a Firestone mechanic lo those twenty some years ago, we'd drop a tranny and throw clutch plates in all the time (book time paid more time than it took me to do it). Neither of the local Firestones would touch it when I called.
Point is, automatics are pretty sturdy these days, and there are fewer shops in the U. S. that will work on manuals anymore.
Most modern DCTs are wet clutch which should last more or less forever. Ford/Volvo's dry clutch DCTs probably still require regular clutch plate replacements. Torque converters pretty much last forever on infrequent fluid changes or the whole unit fails.
Ford's dry clutch DCT (used only in the Focus and Fiesta, all of the other Ford/Volvo models are wet clutch) is total junk and you're lucky if the clutch lasts more than 30k miles. They lost a class action lawsuit over it.
A lot depends on the transmission. In BMW land you can take apart the automatics and often get parts for them. The manuals rated higher for higher power (e.g. the Getrag 420G) you may be able to take it apart (even then you'll want specialized jigs), and you may be able to put it back together (with a monstrous press), but you still won't be able to find new parts for it.
Meanwhile you can take the automatics apart in your garage with few-to-no specialized tools.
They may be, but probably not enough so to offset what having a manual transmission does to the resale value of your car in the USA.
I'd be willing to go with a manual on a used car that I am paying cash for, but, if you buy a new manual and need to finance it, you'll likely be upside down on your loan for an uncomfortably long time.
I've heard part of the reason automatics caught on more in America is because Americans had more relative buying power, so manuals being a little bit cheaper wasn't a big deal. Same for better dryers, bigger houses, bigger cars.
