i may be wrong here, but if i remember correctly, in ech, essentially our first communication is done with some central server (which as of now is mostly cloudflare) and then they make some connection with target server, and then a channel is established between us and target. my google-fu brought me this , which is basically this only

https://cf-assets.www.cloudflare.com/zkvhlag99gkb/3C9ceBTx5AQXu8tS0lgzdF/55ea89f5a56843db15296b2b47f7b1c2/image3-17.png (https://blog.cloudflare.com/encrypted-client-hello/)

I am unfamiliar with QUIC, and quick search basically tells it is kinda like multilane highway for udp.

If I have to compare, (not a network engineer or a person who has studied networking, to me anything beyond the simple protocols seems magic), QUIC seems like a techt which is only used after you have made connection with target, so its implementation is google independent (they seem to be lead developers for this). Whereas in ECH, cloudflare are the primary devs, but also the holder for the public keys (someone else can also be the holder, but i dont know of any other provider currently, maybe my lack of knowledge here)

Essentially just an extension of your point that implementation is lacking

for me, currently the problem is over reliance on Cloudflare, which is yet another big tech company

that seems to be a solvable problem, you can add pretty good fail proof (read resistant) valves. And the retraction can be controlled to never let any fuel come back, so even if the hoses catch fire, they would pretty quickly dry out. Combined with good sensors, these could outperform modern stuff in theory. (or atleast I believe so)

I can’t think of any downsides, besides the increased construction cost (not really sure how much increase, considering the ground space required is less, and no digging, but designing hanging fuel tanks, maybe about 1-2 tons of fuel would be hard) and limit on the capacity stored. Why were they discontinued? Was the disaster risk any higher. My initial guess it that any body driving and smashing the pumps is not present anymore, they are built high enough to not be hit by trucks.

the safety factor got me