The asymmetry stems from the days where we connected through the phone lines, which was not designed for data. There it was possible to have a higher bandwidth out from the phone switches than in. That is, dial-up modems and DSL modems could have a much higher download speed than upload.

I don't know about cable, but I suspect it's the same there.

OTH, fiber-based internet often has symmetric speeds. Don't know the stats, but I suspect most fiber ISPs gives you that.

The asymmetry stems from ISDN. Bonding pairs, twin lines, etc etc. that bled over into the dialup era and bled over still into the cable internet era and has even bled over into the satellite era.

Fiber internet often gives you 1Gbps up.

Fiber isn’t available in 95% of the US. They give you 1Gbps up because they don’t really have saturation.