Yes, but very limited. They are only allowed to ask "are you a US citizen", and walk a dog around the car. I've never had one take more than 60 seconds in either AZ or CA.
I'm a tall middle aged middle class white man and I had no issue with any police check in my life either.
I think there are demographics that have different experiences than mine, especially when there's a dog involved (who can provide any excuse necessary:)
I don't believe police at checkpoints in Canada are walking dogs around the car or asking whether we're citizens or not, it's just a matter of whether or not someone's had drinks, I'm fine with it
In Australia I've been stopped many dozens of times for a "random breath test" where they stop every car and make you blow into the device to check blood alcohol.
As a Canadian, in Australia, I was surprised by the random breath test. That is not allowed at check stops in Canada unless there is another reason to suspect you have been drinking (smell of alcohol, slurring words, that sort of thing).
I think there are demographics that have different experiences than mine, especially when there's a dog involved (who can provide any excuse necessary:)