The balcony appears to have full coverage on the railing - there isn't a gap at the bottom for anything to fall out through. The metal frame makes it looks like there is at first glance, but look at the seam on the glass - it continues further down than that bottom crossbar.
This might fall over into the balcony some day and break but it shouldn't really be a hazard to anyone else.
Beyond this, the reality is that plenty of the other balconies likely have string lights or other electronic items plugged in 24/7 and with their connectors sitting on the ground on the balcony. Same with having a bunch of unsecured/poorly items that could theoretically get tossed off it by an extreme storm. Not ideal, but I don't see why we should be acting like this is much different from everything else in that sense.
------
Now speaking more generally:
- Cities should have reasonable regulations (and likely, already do) about securing anything being positioned where it could fall off and hit someone, particularly over a sidewalk or public space. (As mentioned, I don't think this one is a major hazard upon taking a second glance).
- Balcony solar kits should probably at least ship with some safety cabling and have integrated mount points for those cables that are sturdy enough to withstand wind + drop shocks.
- My concerns in the US/North America are more around how we handle the much lower ratings of our typical residential circuits, it's easier for a consumer to overload a circuit here with something like this than in Europe.
- If we're not requiring a dedicated circuit/single-outlet circuit for it seems difficult to maintain safety unless we're capping the maximum power per system quite low. And if we are requiring a dedicated circuit for it/an electrician to approve it we're greatly limiting who will ever be able to install these.
Overall though, I'm still positive on the concept and don't want to see it buried in regulatory hell, especially with how well adoption has apparently gone elsewhere.