Factorio Forums

I noticed that while a normal Assembling machine 2 requires following ingredients:

• 2 x Steel
• 5 x Iron gear wheel
• 3 x Electronic circuit
• 1 x Assembling machine 1

...choosing Expensive Recipes in world generation, the ingredients are:

• 20 x Iron plate
• 10 x Iron gear wheel
• 5 x Electronic circuit
• 1 x Assembling machine 1

So Steel got replaced with Iron plates which feels counter-intuitive as Iron plates are easier to manufacture. I kind of expected to simply need more Steel for Expensive recipe.
Tried to check other recipes too but didn't find any other cases on quick glance.
I found post on subreddit where someone else encountered this same problem

Meh, advanced search has failed me this time. Sorry for duplicate.