The problem is that ATO relies on the underlying technology to be working and maintained. Maintenance requires money, which WMATA doesn't have. That's the issue

The problem is that ATO relies on the underlying technology to be working and maintained. Maintenance requires money, which WMATA doesn't have. That's the issue. Humans don't require maintenance the same way something like ATO does. Politicians continue to underfund WMATA, which means they can't assure safety using an automated system, so that have to use humans.