Perhaps a person's interests, income, or lifestyle are salient variables as well? I would guess that each person's circle of friends has some of these in common in addition to age (likely true for HN discussions as well). For a less biased picture, here are some statistics about tablet use by age:
It's striking how uniform the distribution of tablet use was across age! There was a bump after age 25, though that was mirrored in the iPhone usage. This is really salient at the low and high end: age 0-18 was 20% of tablet usage and only 6% of iPhone usage, and age 55+ was 20% of tablet usage and only 14% of iPhone usage. Given all of this, it seems like tablets are quite broadly adopted devices
https://www.statista.com/statistics/805143/us-tablete-users-...
and for a baseline, iPhone use by age:
https://www.statista.com/statistics/203063/iphone-users-in-t...
It's striking how uniform the distribution of tablet use was across age! There was a bump after age 25, though that was mirrored in the iPhone usage. This is really salient at the low and high end: age 0-18 was 20% of tablet usage and only 6% of iPhone usage, and age 55+ was 20% of tablet usage and only 14% of iPhone usage. Given all of this, it seems like tablets are quite broadly adopted devices