I think this is a bit OTT. Most young kids these days don't just 'decide to visit' a friends' house, their parents arrange playdates - exactly the same as the royal kids.
You could say the same about kids born into poverty, for example, many of whom don't get the opportunity to travel or learn an instrument or participate in everything they'd like to do. Even 'average' kids can't afford to do expensive hobbies like sailing, racing, etc.
The RF can do anything they want. They could choose to study abroad if they wanted more anonymity, and when they are older they could even choose to do a Harry and opt out completely if they wanted.
Other than George, the other two could have very normal, albeit financially comfortable lives - realistically would your average person on the street know the names of Princess Margaret's kids and grandkids, or even Prince Edward's kids? That's the level Charlotte and Louis' families will be in thirty years.
I personally would prefer there to not being a monarchy but my view of booing at TtC is the same as anything else - event/TV show/band - if you're not interested in it, don't go! Going just to piss on the chips of everyone around you by telling them how rubbish the thing they like is and how much of a moral superior being with better taste you are for not liking it is just a bit pathetic, more so when you bring kids into it.