As much as I like the freedom to tune, it's also a nightmare over here and it needs some control. As it stands, you can do pretty much anything to your car and as long as it'll pass an MOT, then it's golden. No checks are made on the quality of the parts or work. We're not talking about "us" as such, but look at some of the crap on the roads that's modded and you'll see why.
When I go to shows and whatnot, I'm never ceased to be amazed at the dangerous and disgusting work I see on cars in the name of 'modding'... cages held in by self-tappers, you name it.
There are many, many dangerous cars on the road that because of the outdated MOT system can drive on the road. I don't want them near me, or anyone else I know.
In Germany you can mod your car, but with caveats. You can do 90% of the mods we do (cages are iffy, unless you can prove it's for competition) and when you take your car for its annual check, you have a log book containing the list of everything extra/different about the car. Everything in that log book is checked in addition to the normal routine and is signed off as safe. The parts HAVE to be TUV approved - so no dangerous/untested Chinese et al tat off ebay.
Checking ECU's for maps?? I can't say it'll be widely checked, more kept in the bank when finding evidence for cases against dangerous driving etc. But the rest of the MOT and modding scene I'm 100% behind them in updating the regulations around it.