There are practical limitations that prevent us from doing that in the US. Specifically, our ballots tend to be long and complicated. A California ballot on a p

There are practical limitations that prevent us from doing that in the US. Specifically, our ballots tend to be long and complicated. A California ballot on a presidential year can have dozens of contests, from president to dog catcher to referenda. Reading out all ballots would be very time-consuming and likely very error-prone as poll workers are pretty tired by the end of the night. This is why we have scanners to speed up counting paper ballots. And paper ballots are retained for targeted manual counts if there's a need for auditing or recounts.