First of all: there is no difference between “robber baron” and “industrial revolution”. The only difference is that they had different level requirements in legacy. This looks a bit uninteresting.
What about either (1) give them different purposes or (2) merge them into one card?
I think it makes more sense if robber baron is an American-specific card (either with or without unique traits) because that term is American:
And also I have a more radical thought. Not sure if it is practical, so I’d like to know what people think:
The 2 factories card may be the only cards that you MUST put into the deck if your civ has them (maybe 2/3 vils also?). The thing is, this is not an intentional build or strategic decision, but because if you don’t do it, you’ll be at a serious disadvantage once the game reaches age 4. I don’t see anyone, even those going for rushes, not including them.
On the other hand, the inclusion of most cards is and should be the result of strategic thinking (military or economy, quantity of quality, rushing or fast age-up, and whether to prepare against certain possible strategies from the opponent). For most of the cards you might actively consider whether or not to include them. Factories do not. You do because you have to.
As a result it effectively leaves the European civs a 23-card slot to decide on. Not 25. Imagine if there was a card that unlocks dragoon-type units at age 3, and it is so important that everyone includes them. It does nothing but wastes a card slot. I think such a thing should be a default feature, not something you’ll need a card to unlock.
Of course factories are too powerful if they can be directly constructed by villagers. So here are some possible ways NOT to overthrow balancing:
(1) Like the US. Directly deposit the 2 factory cards into your deck once you reach age 4.
(2) Make them techs that costs shipment points. It has already been done in the NE mod. As for which building, maybe move the capitol to age 4 and add the “factory tech” to it:
BTW: I think quite a few cards that look as if they were originally techs in the earliest designs should now be reverted to techs. Now that the strategy of the game is very well established (unlike the earliest release), we are pretty sure that some cards will never be used. Moving them back to techs would give them some possible use.