But it is easy to get thrown in jail. This is especially true if your skin isn't white enough: How many stories do you hear of folks being in jail for having the description, "Tall black male?".
You act like everyone can avoid all things: Have you never met anyone put in jail for not paying child support when they don't have a job... in part, because they were put in jail for not paying child support?
Or... you can live in a weed-friendly state and forget you have some in your car while traveling. Jail for drugs now. Heck, you can be jailed for being in a house with drugs, even if you weren't doing drugs yourself. "Visiting a common nuisance" is a thing they charge folks with [1]. I don't think it is as common now, but at one time, it wasn't uncommon to get arrested while walking home drunk for public intoxication, even though driving would have been criminal. Indiana cops used to wait outside bars to arrest folks for this. While it might be prohibited now, this ruined lives and stuff like this still happens.
You don't have, "many chances". You just get caught or you don't, and you can get caught your first time. It happens. For some things, simply living in public housing increases your chances because of heavy police presence that isn't there for nicer neighborhoods: Sometimes nicer neighborhoods have conditions that make getting caught less because you are smoking weed in a spacious backyard rather than on a balcony where others can see and smell.
[1]https://www.in.gov/meth/files/Visiting_or_Maintaining_a_Comm...