The government only requires the vehicle to be in a technically correct condition, brakes, undercarriage, shock absorbers, control elements, electrics, exhaust gasses, etc...
Who makes the repairs don't matter at all as long as they are technically sound.
I got my current vehicle new 13 years ago, I opted to get an annual service made by an official service shop.
I will keep doing so as I like to sit into my car and take an unplanned 1000km/10 hour road trip one way without having to worry about reliability of my vehicle - never failed me yet, knock on wood.
Although, rust is taking it's toll.

My brake concerns are also rust related, I guess I don't brake enough to keep the front tire disks polished clean.
I was taught to maximize the engine for braking (5 gear shift stick in my current vehicle), when there is very little traffic I can get to and/or from work without ever touching the brakes, saves fuel too.
This was 4 months ago when I switched from winter to summer tires, outside looked OK
View attachment 137627
but the inside not so much.
View attachment 137628
I checked this morning and it looks a little better now than four months ago.
I am forcing myself to brake more often and much harder than actually needed - it appears to have helped cleaning the disk a little, still the inner pad is unevenly worn and doesn't touch the disk towards the disks center.
Brake test is positive and withing specified parameters (as said, I had it checked today).
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I think the main cause for the above was that last year I requested the service shop
to replace the pads and if needed the disks too - they said no need to replace the disk,
I should have insisted!
Pads were damaged after 12 years age, the damage went unnoticed by the service at two unscheduled visits by me claiming noise from the front tires, third visit I had them lift my car and pointed to the loose pad and broken pad areas - then they agreed it needs replaced.
The top pads were the inner ones, the bottom pads the outer, the pad that broke off the steel plate made the noise and was held in only by the disks radial wear - that could have been nasty had it ever slipped out.
View attachment 137637
Generally I'll have to replace the disks and pads as the unevenly worn disk will only unevenly wear any new pad.
The joys of owning an aging vehicle.