I have bought 5 year old cars for £5k because that's my budget. I go to garages that get checked out by trading standards, have liability insurance, also offer a warranty of at least 6 months on every car they sell. I also pick certain garages because they have a good reputation.
Secondhand bike market is any Tom, Richard or Harold who has possession of a bike they want to pass on for money. I think I can sniff out the dodgy but no guarantee. No idea if stolen, no trading standard to investigate should it go pear shaped. I'm on my own with potentially a bike that needs much more spent on it to get it roadworthy than it's worth.
Of course it might be a stereotype to say that most supporting the petition and secondhand over new potential BSO are the sort to be into bike maintenance with a box full of spares for such a used bike. I'm not. I have no. Interest in playing around with bikes in a man cave even though I now have a garage and can do it to a certain level.
I'm not the only person like this but I at least have an appreciation of better bikes and own a few. I also have an appreciation of the circumstances of someone buying the BSO. It's still a very valid option and it's elitist to say that option isn't allowed. I say get on your 1990s kona rigid mtb, go out to find your next project and let others ride their bike choice how they like!
PS I'd rather have a road filled with BSO riders than a ban on them.