If you keep getting hit with the bar, you are doing it wrong. Why is it a surprise? Sit down. Lean back. If you are tall, duck once you are on the lift. OR... Sit down, get your hand on the bar ASAP to control the situation. Expect the bar, don't be surprised. Like others have said, some areas mandate the bar down immediately, especially if kids are on the chair. So, the practice has spread when people from those areas travel.
If it's uncomfortable after it comes down, ask to raise it up again. Or speak up as it comes down if you need to move a bit. I've been on a couple chairs where the footrest was for kids. For those, I have put the bar down the first time, then raise it up shortly after because it's uncomfortable. Majority of the time, this isn't the case.
Sometimes when I ask to lower it, someone gives attitude or sneers - "If you must" or something to that effect. Like it's a macho thing to have the bar up and safety is for weenies. It's for those people I don't even ask anymore. I just say "Coming down" or "Bar" and lower it. I don't need to hear sarcastic or macho comments. If I see someone is clearly in the way, I don't drop it. I've had glancing hits from the bar on my helmet. It doesn't hurt. Usually my fault for not getting on the chair quickly (ie trying to do stuff while loading, like removing gloves, pole straps, etc).
You have to be way out of position to get really smacked by the bar.