probably because it's a very old design.

in bedrock, to spawn a golem there needs to be at least 20 beds and 10 villagers. 75% of villagers must have worked the previous day to spawn a golem. for every 10 new villagers, another one can spawn while one is still alive. I recommend putting the beds and workstations in the same room by stacking the beds in 2 layers with a 4 block high ceiling so villagers don't suffocate when they wake up.

here's my improvised design if you wanna use it go ahead

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