Your comment sent me on a bit of a rabbit hole, it turns out you can look up commute distance histograms in the census data here
https://onthemap.ces.census.gov/I looked at a few dozen cbsa metro areas, big cities, small cities, east, west, middle and the only 3 i could find with more people traveling 10-24 miles than <10 miles were Houston (34/36), Dallas (34/37), and Atlanta (34/38) so even in the worst case ~⅓ of commuters are doing less than 10 miles.
I couldn't figure out how to query this data via an api, but I did find a paper that looked at the 96 largest metros, which showed that Houston, Dallas, and Atlanta had the highest median between 12.2 and 12.8 miles. So I think that a 20 mile average is likely not true anywhere, though double digit over 50 miles does occur in all three of the above cities. Most cities have plenty of people commuting across the spectrum, though some are significantly denser than others (up to ~45% for <10).
Now looking at the per mode data, 10 miles is still on the long side for a bike commute. There is a steep drop off in people cycling/motorcycling to work (for some reason combined in the dataset) at the 30 minute mark. 20mph is fast even with a e-bike assist, probably somewhere around <2-6 miles would be the ideal probably.
I do agree with you that most people aren't going to start using bike lanes if that means a worse commute. I used to, but I cycle for sport and would do those hours anyways (now my bike commute is faster than train or car). Most Dutch people don't bike commute for fitness or sport or fun, they do it because it's the most efficient way for them to make their daily trips. Part of this is because of the density of that country and part of that is the infrastructure.