1990s: ~%36 of all teens smoked
2020s: >%2 of all teens smoke
Kinda suggests that putting limitations in place actually produces results. Crazy innit?
Cigarettes have been age restricted for around 100 years. Not related to your 1990 to 2020 time period at all.
If you weren't aware, smoking became uncool a long time ago. Teens who consume tobacco use vapes or Zyn now.
It also means we don't need identity verification. Anonymous scratch-off cards sold in stores to adults, just like cigarettes, can be used to verify age. Or alternatively, device-only attestation. There's no reason to verify age upon every use of the product; only when it's sold.