The frequencies they come programmed with are probably legal in some parts of the world.However, every country allocated bands, and frequencies within them to certain services. Some are accessible legally with a licence, some without, and many with big fines or worse if you get it wrong.
It’s probably fair to say that almost certainly buying one and just using it will be illegal in most countries, but thousands of people may buy radios on amazon and just use them. As the range is small, and geography critical, most of them get away with it, by luck. The risk is still real though. Using a radio in a location where your use becomes very obvious - let’s say you live near a port, and are chatting away on a channel that other users will notice, means a probable visit from the authorities. At best, confiscation and at worse a fine. If the people you annoy are important, then think worse. If your use causes something really serious - maybe you’ve jammed an ambulance service radio and somebody dies as a result - then expect punitive and decisive action.
Hams should know all about frequencies and licence types. family and small business radio users probably less so.You need to research your own legislation and determine what you want to do. In the UK there are frequencies for licence free radio channels. Strictly speaking programming one of these via Chirp breaks the law, but if you are happy with lawbreaking - I doubt people will know, but I suppose it depends how illegal operation sits with you. You really should use them only where it’s legal and legit. I think the advice should be to NOT use them unless you really understand what you are doing and the consequences.