4/ those who have 3 different resources in their cart get as many points as there are red-roofed buildings still to be placed in the village (so 12 points the first time)[...]
In case of equality, the winner is the first one who placed a building.
Using this variant, the critical phase occurs early in the game and this could lead to a lost of interest when a few (and occasionally "not so few") buildings are still to be placed since the winner could already be known even the later has placed less buildings than the former. Furthermore, it seems unfair in some situations.
Let me present some examples of 2-player games(for sake of simplicity) to illustrate the point (A and B refer to players):
Sequence of building: A-B-A-B-A-B-A-B-B-?-?-?
player A (4 buildings in the village) = 36 pts (advantage)
player B (5 buildings in the village) = 36 pts
There are still 3 buildings to place in the village and B has to build the 10th or the game is decided in favour of player A, regardless B has built more buildings than A by now and regardless B places the 11th and 12th buildings, totalling 7 buildings (against 5).
Sequence of building: A-A-B-A-B-A-?-?-?-?-?-?
player A (4 buildings in the village) = 39 pts (winner)
player B (2 buildings in the village) = 24 pts
Note that even player B places in the village the remaining 6 buildings, totalling 8 (against 4), player A is the winner.