the lady with the sign that caused the crash 2(?) years ago had no consequences at all, not even fined.

Are you sure about that? Maybe they ended up waiving the fines in the end, but reports at the time were that she was arrested and fined, and that for a while there was a possibility of jail time:

• https://www.cyclingweekly.com/news/tour-de-france-opi-omi-spectator-arrested-according-to-report
• https://www.cyclingnews.com/news/opi-omi-spectator-fined-euro1200-for-tour-de-france-crash/
• https://www.cyclingweekly.com/news/tour-de-france-opi-omi-spectator-avoids-jail-sentence-after-causing-stage-one-crash

the police that’s around the route and especially on mountain stages are extremely passive. They just stand to the side and watch the show without doing anything at all.

They can't police every fan on the side of the road. The person who caused the crash today may have only been in the path of the race for a few seconds, leaving no time for any sort of police action.

There's no reason to think this person today intended any malice. Same with the woman with the sign a couple years ago. It was carelessness and lack of understanding of just how fast the peloton rides. Maybe it would help to make some examples out of some people by fining them, but I'd rather start with educating the spectators first. There should be signs along the course, in the towns or on the climbs where people park, etc.