My best guess is it's a busy road so it's dangerous and not really meant for bicycle and walking. I've done 13 miles yesterday to get a comic book on a bike and this right here is the distance between my house and a friend's house I told I can come on bike because what I just did gave me a feeling I could do it but my ass hurts so not right now. But yeah I want to see how this would play out. Before I would walk but I took a bike to a comic book store because it would've closed if I walk and I ended up getting there in time. Took longer than expected something that should've been an hour probably took 2 or 3 hours. So yeah I can do half of that for sure.
A lot of the bike routes are mapped using car data. If you are biking on a one way street and have to turn around, maps will route you around the block (uphill) like a car, even if there's a sidewalk you coukd bike or walk down instead.
It's not super great for biking data, but it works. It tends to miss protected bike lanes, though.
I don't think it has trouble with bike routes.