Iron golems don't spawn

There needs to be a lot of villagers for a iron golem to spawn.

yes i know but i never find a iron golem also on 3 villages in one seed

Iron golems spawn, but they are super rare, The chance of spawning is 1 in 7000 per game tick, check the minecraft wiki. Also they spawn centered between the 21 or more valid doors in a village if it has at least 10 villagers. In mcpe I saw 1 iron golem spawning.

most of the time you have to make houses and let the population grow. i'm not even sure if villages could be auto generated that big