I would hope not, but how realistic of a concern it is depends on your neighbors, the local CPS folks, and how well you’d come across to them at the time. It adds a lot of fear, uncertainty, and doubt.
That near as I can tell no one lets a kid out alone is indicating how big a problem it really is. The most I’ve seen here is when they’re paired up and 12+, and here is one of the safest places in the county in a very child friendly place, literally 2 blocks from the police station - and the police here have some of the best reputations in the country.
This absolutely depends on local CPS, and they have wide authority within their lane. As they should, considering their mission and the interactions and choices they have to make in bad cases.
But it does mean that a lot is subject to opinion. And once you're on the radar, how do you get off? How do you prove you're a good, safe, responsible parent when the judging worker believes otherwise and has some authority to make that fact?
By being a good, safe, responsible parent. You all are acting like CPS pulls kids away from stable homes on the daily. That isn't happening. This is a consequence of anecdote over data, where there is one or two widely bad outcomes and everyone reacts to them, when in reality, this almost never happens.
I, and nearly everyone in my neighborhood let our kids out. I see kids walking up and down my street, by themselves and with their friends every day. Let your kids go out, they and you will be fine.
Here in the bay area, I only know 1-2 areas that are like that, and even then you'll only see teenagers. Might end up moving if one is local! I'm in the lower peninsula area.
I live in Washington, Puget Sound Area. Kids out all the time, plus no income taxes, reasonable property taxes, and a great, though limited tech scene.
The PNW isn't for everyone, but we know how to get outdoors at all ages :).