There may be a valid reason besides "too cheap" to not use a metal crimped seam. Maybe gluing the seam provides a better seal than a metal crimp would on that wire-backed media design, and adding a metal crimp to an already glued seam may not be necessary.
The seam almost looks like it's "heat fused" together. Until I see evidence that the seam fails in use, I wouldn't be worried about it. I'm sure the engineers found it is robust enough on a filter that's rated to go up to 25K miles.