Your frustration is understandable, but these limits are due to third party add-ons and the rules of specific server admins (i.e. they're not LFS's 'fault'). Some server admins want to try to ensure that only people who are at least a little experienced on the current car/track combo are allowed to drive, so they apply these limits. Whether this is a good policy or not is debatable, but you shouldn't blame LFS for them.
Unfortunately, the current state of public racing in LFS means there isn't often a lot of choice, so you can get stuck with the same handful (or perhaps even 1 at certain times) of popular servers to choose from. The 'blame' for this is also debatable.
In short, if you want to enjoy public racing in LFS at the moment you'll probably have to put up with these limits. The good news is that for most people the limits aren't really that difficult to achieve. Just find another server with the same car & track (or find an empty server where you can change the car & track to match) and do a few laps to hit the target laptime.