This question has been asked before...
...but there's a very specific part I'm struggling with, and it's not addressed in that post.
Part of what causes friction is the breaking of microscopic ridges in the materials sliding on each other, protrusions that catch and need to be dislodged.
Let's say it takes a certain amount of force to break each of these ridges.
If the two surfaces are moving faster relative to each other, they would need to dislodge more of these protrusions in the same amount of time. It seems to me, then, that kinetic friction (at least between rough surfaces) should be velocity dependent. However, the standard explanations say it isn't.