I also think that people just don't know this rule. Or they don't find any sense in climbing the escalator and saving what - 3 seconds? instead of standing still. Isn't the point of escalators to actually avoid climbing stairs? Besides as you already know Bulgarians love to break the rules accompanied by the routine reply "Who are you to tell me what to do!" What's more Bulgarians in general don't care about others. Entering the metro don't make an exception "It's only me who matters and I don't care that you want to get off".