They seem to count ALL forms of travel (walking, biking, driving). Also the definition of a trip is to go from one address to another. So when I walk over to my neighbors house across the street it is technically a trip.

https://nhts.ornl.gov/vehicle-trips

For vehicle trips:

21.4% of trips are 1 mile or less.

35.2% of trips are 2 miles or less.

45.6% of trips are 3 miles or less.

I don't think "usually" is close to accurate. People go to work, restaurants, friends' homes, etc without transporting any cargo. Big grocery runs are maybe once a week.

There are bikes that can take fairly large loads[1].

[1] https://en.wikipedia.org/wiki/Freight_bicycle