In Austria a big reason are old rural rail lines. It’s not trivial to install automated gates without having to remove some stops or keeping the gates down for very extended periods of time.
They are also not entirely safe because people are idiots and get stuck without understanding that they can actually push through the barrier.
Ones with nothing except signs to stop, look and listen. You're most likely to find this while hiking, as a footpath crossing.
Flashing lights and beeps.
Half barriers, which only cover half the road (one lane in each direction). These are my automatic. Drivers can't get trapped.
Full barriers. These all have CCTV, and the train won't get a "green" until the signaller has seen both barriers close, and that no one is in the middle. These are used in cities and other busy places.
One other fun type are the user operated gates. Normal farm gates on both sides of the railway, with a red/green aspect light telling you if it is safe to open the gate. Once you've driven through you have to stop and then close the gates. Last time I used one of them, by the time I walked back to close the first gate the signal had gone red so I waited.
We also still have some full barrier crossings operated by a signalman near me. There's something pleasing about that.
Germany has a lot of them on mostly remote, rarely serviced lines that see only a small number of regional trains per day. Main reason is cost to upgrade weighed against the (relatively) low risk of incidents because of low amount of traffic on both the train route and the crossing road.
I live on the same block as a urban street level crossings that just have lights. People routinely cut through the light. That line just goes to the factories so the trains are going pretty slow, or sometimes stop on the signal. There is a gated crossing a little further down the same street for a thoroughfare and cars routinely race the gate to avoid waiting for the train there too.
One could argue all those people are insane, but there are a lot of them.
I've seen people cross on red lights. Sometimes it's the impatient person who has to get through as it's closing.
Sometimes it's the impatient person who is tired of waiting as the signal has been going for minutes and there's no other evidence of a train.
Sometimes it's the inattentive person following the car in front.
Gates help the third person most. I haven't seen many crossings without gates, but they're a lot easier to miss than a gate.
Protecting people from a train collision has benefits for the train system as well. A collision causes confusion and delay and may damage the rolling stock or even the rails and could cause injuries and the operators likely need PTO. So it's rational to reduce collisions regardless of opinions about the choices of the participants.
