I'm assuming placement is based off of your estimated pace/finish.
I can’t speak for runDisney but that is usually my experience in races over here, but not this weekend! In general, fewer slow runners participate in races in Europe (or maybe it is only Switzerland). I am always truthful about my times, but normally for a 10k here there will be various choices and then > 1 hour. I know I chose that for the race I just did on Saturday, as did my bestie - she’s faster than me but still takes her just under 1h10 for a 10k. The 50 minute pacer was in our corral! And despite trying to stay as far to the side as possible, there were numerous runners who pushed their way through - I was just glad no one stumbled.