Whats the packet loss rate on modern networks ? Curious.

~80% when you step out of wifi range on your cell phone.

… from 0% (a wired home LAN with nothing screwy going on) to 100% (e.g., cell reception at the San Antonio Caltrain station), depending on conditions…?

As it always has been, and always will be.

It can be high on cellular.

Pretty bad sometimes when on a train

That depends on how much data you are pushing. if you are pushing 200 mb on a 100mb line you will get 50% packet loss.

Well, yes, that's the idea behind TCP itself, but a "normal" rate of packet loss is something along the lines of 5/100k packets dropped on any given long-haul link. Let's say a random packet passes about 8 such links, so a "normal" rate of packet loss is 0.025% or so.

Once it makes it to the long haul links. Measure starting at your cell phone and packet loss is much higher than 0.025% and that's where QUIC shines.