Unfortunately I think the media has really mixed up the words "presymptomatic" and "asymptomatic". You're right there is little evidence that people who never develop symptoms can spread COVID. But it seems likely that COVID can be spread up to 48 hours before symptoms develop, which still presents roughly the same problem.

Here is a paper looking at viral shedding over time in COVID patients: https://www.nature.com/articles/s41591-020-0869-5

I also anecdotally know a few different people who caught COVID from someone who felt fine at the time they interacted, so I'm quite confident it is possible, although I'm not sure I'd make a strong statement about the prevalence.