This is from 93 and probably dated, but explains the required inspections that drive "old" cars off the road.
Why the Cars In Japan Look Just Like New
Wikipedia :
Motor-vehicle inspection (Japan) - Wikipedia
Although this is old, it's fairly accurate even today. As stated, the actual inspection is relatively cheap (it's about $15 today). There is a system called "User Shaken", referred to at the bottom of the piece, that allows the car owner to take the vehicle through the inspection line him/herself. As a person who likes to tinker and is not afraid to get his hands dirty, I've been doing that for years.
The kicker is that auto taxes have to be paid at the same time the inspection is conducted, which constitutes the majority of the cost, and the entire process is such a pain in the neck that many just opt to take their car to a shop where often times things that really don't need to be changed are changed, and at dealer prices to boot.
Over ten years ago I took a Subary Legacy in for the inspection. I had done all the prerequisites (measured brake pad thickness, checked fluids, cleaned CV boots (not kidding)). Went through the first part of the test which consists of:
1. A 'slip test' that checks for play in axle joints, suspension etc.
2. Speedometer check (drive on rollers at a dictated speed)
3. Brake check (parking and regular) performed while on the rollers
4. Headlight aim (shine headlights into a robot that rolls out in front of the car while on the rollers)
5. Exhaust check (put a sensor in the exhaust and wait for results).
6. Then the pit
I rolled over the pit and the guy below bangs and pulls on things (steering joints, checks for loose bolts, exhaust leaks, etc.) and then pulls, with a metal hook, on the CV boots. I hear the guy from below the pit say "please get out of your car and come down" (in Japanese of course)
. I go down into the pit and he shows me a torn boot. I know it wasn't torn before I got there because I was under the car checking and cleaning them. They were admittedly old and brittle but it was clear that he pulled the boot with his metal hook and separated it in one of the deep crevices of the boot.
With no recourse, I drove the thing home flinging grease everywhere under the chassis, got a new boot, took the assembly apart (quite a job), replaced the boot and went back the next Monday (the original inspection was on Friday so it consumed a good part of my weekend). No problem after installing the new boot.
Anyway, the whole system is very demonstrative of Japanese culture in that there is a strong sense of specialization and willingness to let others, specialists, perform tasks that are in their realm. More people today do "User Shaken" but the majority still go to a shop or dealer and pay dearly to keep their cars in virtually new condition.
Having said all that though, there are serious car fans who do it all themselves...probably not as many as in the States though.