Why are election results shown at the end?

Voting is very, very decentralized. Votes are conducted at the county level, which is then reported to the state, which then reports to the federal government. The laws each state and even county have on how votes are conducted differ, so different methods are often used, and of course, because of the electoral college, the straight count doesn't always matter anyways.

So, at least for the Presidential election, there's a lot of reason not to do this. It'd also probably be bad to have the counter increment in a voting place when you submit your ballot, because then you would see how the person in front of you just voted, which we don't want, so people aren't bullied about how they voted.

And finally, technology does not actually solve problems: It trades problems we have for new and potentially bigger problems. For instance, if you are reliant on a digital system for counting votes, it is easier to tamper with and harder to verify that tampering has occurred. This is why if you want to be sure your vote actually was counted correctly, you should always vote on a paper ballot if it is offered in your district.

Wouldn't that cause an observer effect? If I see my candidate is losing by a landslide maybe I'll change my vote. But I would have been influenced by incomplete data