This isn't the 1970s anymore. Very few cars have major repair costs from engine problems. People are just creating an elaborate narrative of cost savings.
Insurance cost data doesn't seem to bore this out. BEVs have pretty decent maintenance costs.
Before switching to hybrids, I literally spend thousands of euros fixing my VW diesel that was worth maybe 10k€.
The dual-mass flywheel broke, that was 1k€. Had to do a clutch repair at the same time, 700€. The turbo started acting up, that was around a grand with all the labour. When the turbo was fixed, it clogged the already close to full diesel particulate filter. That would've been 2000€ to replace, but I knew a guy who just emptied the casing and modded the software on the car to think it was still there.
Finally a tiny hexagonal thing at the bottom of the engine broke, which prevented any oil from circulating in the engine. That would've been a 2000€ operation. Had my guy do a quick patch job with some bonding agent, sold the car.
...and that's on top of the normal wear and tear + yearly oil changes etc.
The car was under 10 years old at the time and 90% of the problems were issues with the overly complex drivetrain with thousands of moving parts, instead of just one like with electric engines.
On the hybrids I owned all the issues were in the combustion engine. On my current EV all the problems are unrelated to the drivetrain - currently the AC can't hold its coolant for more than 6 months, haven't found the leak yet.
That's likely a deficiency of your VW diesel. VW never properly designed them correctly, and that includes not meeting emissions. Other car engines likely won't have that many issues.
Once you deal with the eventuality of a dead battery, it will easily trump all repair costs of ICE cars. People are just pretending it won't happen to them.
Also, an FCEV is an electric car too, and doesn't have that many mechanical parts either. It also lacks a giant battery. Basic engineering suggests it will be the cheapest type of car of all to maintain once they hit critical mass.
In the long-run, this will be very small. They do not have huge resource requirements of batteries. Though at the moment, these things have zero scale so repair costs are exaggerated.
Insurance cost data doesn't seem to bore this out. BEVs have pretty decent maintenance costs.