system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What are all the people doing on the floor of the major stock exchanges, and why can it not be automated/done from an office?
gpt
These days it is automated and they are largely gone, except some will be there to look at their terminals.  

If you go to the NY Stock Exchange, the place is filled mainly with journalists and tv studio set ups to report on financial news and help report on new stock offerings.

But these days the significant majority of trading is done electronically, and a large portion of that electronic trading is done through algorithms, without much (sometimes without any) human input.

Prior to the internet, people on the floor of stock exchanges would do the actual trading of shares.  Rich Bob wants to buy $5 of shares in Coke, so he calls his broker, who receives the order, and sends it as quickly as possible to a man on the floor of the exchange who begins advertising that he is wanting to buy shares in Coke.

Smart Harry told his broker that if anyone tries to buy Coke today, he will sell them his shares in Coke at $1 a share.  So Harry's broker see's Bob's broker and they agree to the sale and register it with the stock exchange regulators.

The brokers take their commission of a couple cents per share, then go off to share a tipple, check out the broads, and definitely not insider trade.