You likely also participate in rituals that were taught to you that are not solely grounded in logic or science. Do you do things in a certain order for no reason other than your parents taught you to do so? Do you avoid eating certain foods because you never ate them growing up?
People who are raised religious may not be fanatic believers, but they may still be “culturally religious” e.g. take part in Ramadan, avoid eating pork, because that’s the way they grew up, and a lot of the time it means they can be included in cultural matters of the community they come from.
As for why some people are proper religious, fully believing and all, I also don’t think all beliefs have to be rational. Some beliefs are comforting. If it helps someone to get through a difficult time by believing there’s a higher power rooting for them, or who has pre-planned their suffering for a greater good, they may choose to believe that because it’s mentally easier. Arguably that is a rational belief anyway because it benefits you and makes your life easier to get through.
I don’t know about the US specifically, but oftentimes, and definitely where I’m from, laws can have a small amount of “common sense” leeway and judges can find justifications for rulings if they want to rule a particular way. e.g. I have pirated games that I legally bought because there’s literally no functioning “official” download link anymore, if anyone were to ever prosecute me for that, even if it were illegal technically a judge could find a way to rule it lawful out of sympathy or whatever other reason, if they wanted to. A lot of the time it’s “the government can’t have possibly intended this law to be enforced this way, therefore I rule XYZ”.
In any case, as you said, I’ve never heard of anyone being pursued for that. And if it’s not enforced, it’s not a law.