In most jurisdictions, the laws allow allow for production of vehicles ouside of corporations. In Australia standardised design rules apply to every vehicle, and certification by an engineer is required. The cheapest emginerrs' certificate is $2000. But if a motorcycle is older than a certain number of years the rule does not apply. Something which has a different frame but normal engine and gearbox can be registered faily easily.
Many years ago In Melbourne, there was a kid who got a lot of publicity about his hot-rod car. He then bounced it off a rockery which was in the centre of a divided highway. The car flew apoart killing both him and his passenger. The laws changed in every Australian state.
There is still provision for producing your own vehicle, even though we no longer produce cars in Australia and only ever produced one type of motorcycle in a factory..
We do not usually have laws which discourage development.