If you have concerns about their parenting decisions then I guess I'd say no. If they were same sex BFFs would you be feeling the same or is it the fear that their laxity will create 'opportunity', iyswim.
I'm not sure what the problem is with 'wandering around the streets'. I think your wording is a bit 'provocative' and creates a picture of the two of them wandering up and down skid row looking for trouble. My friends (BFs and BFFs) and I used to aimlessly walk around town quite a bit or 'hang out' at the park, there was nothing intrinsically 'bad' or 'wrong' with it and it didn't lead to criminal behaviour. Unless you're worried about their personal safety, I think you're overreacting.
If you don't know the parents that well, are you sure that they're really as lax as you think, or is she just saying that? I admit to telling my BFF's mum, who allowed BFF to smoke, that my mum was 'just fine' with me having cigarettes. My mum would have grounded me until the second coming if she had known! And the fact that they don't give rides doesn't mean they are lax, just that they think the distances aren't 'unwalkable'.
I'm not saying you aren't 100% correct about her and her family. Her manners sound pretty bad, but that's not always indicative of lax parenting, either. Just that perhaps there's more to her story.
Hopefully, this is simply an idea the two of them have cooked up. But if much more is said, I'd speak to her parents.