Everyone dies, everyone suffers injuries, everyone gets sick, it's the price of ever having had the opportunity to exist in the first place.

We've made everything so regulated, costly, and supervised that it meaningfully contributes to the lowest fertility rate in the nation's history. Many of the children who are fortunate enough to get a chance to exist at all spend their lives hypnotized forever scrolling and will likely suffer a shortened and less worthwhile life due obesity, inactivity, isolation, and depression.

Having a chance to live, either in the metaphorical sense or in a literal sense trumps eliminating the last epsilon of risk that can only be eliminated by living in bubble wrap or not living at all.

Your admonishment of there being a middle ground is fair in one sense, but too often humans are bimodal against risk: we either ignore it completely or obsess over it. If a middle ground can be reached, great, but if it can't ignoring small risks is often superior to the alternative of over emphasizing them.

It's also important for to have risky activities that LOOK risky. No one under those bikes was under an impression that it was safe. I'd rather children climb on some lump of rickety boards they hammered together themselves-- it's clearly dangerous to everyone-- than run face first into some gleaming concrete and steel playground equipment which looks safe but becomes just as dangerous if you are reckless enough.

What's safer? Bike jumps over kids or a snapchat filter that makes things look faster the faster the gps reports you going?

... and some amount of the risky stuff is needed just to keep the overton window open for the sensible middle. There are places in the US where children of the ages in the picture merely playing outside (no bikes!) will result in state child protective intervention. If a few kids getting scraped up or broken bones-- or heaven forbid, even dying!-- is the cost of having perspective, it's well worth it.