I'm taking a guess at what the OP meant, but people focus on assault rifles and high-capacity magazines. Supposedly most incidents and deaths are caused by handguns. They're more affordable, and easy to discretely keep on your person. A data-driven policy would focus on them first, but it's easier to rile up the public about AR-15s so we keep doing the less-effective thing.
Things that feel useful instead of are useful.
We're not allowed to use data or experts. They’re untrustworthy and out to trick us.
One might wonder about why ceramic plates are controlled in Connecticut or New York.
It looks like Connecticut first enacted body armor regulations in 1998, the year after the North Hollywood police shootout with a pair of heavily armed and armored men:
https://en.wikipedia.org/wiki/North_Hollywood_shootout#Weapo...
It's hard to find 1998 news articles about it now, but I would guess that the law was a reaction to this high profile crime.