Bug in the villager panel regarding trade cart

For food, wood and stone, the panel incident the number of farmer, lumberjack and stone miner.

However for gold, the panel sum up the gold miners and trade cart.

If trade cart is considered as a villager gather gold resource, why the total villager count in the right hand side of the panel do not count the trade cart?

I suppose if there is no idle villager and no builder, 4 number of resourse should sum up to the total number of villagers

This has been brought up several times before, and people are always divided over whether or not it actually constitutes a bug. I think the best solution is just let people choose whether or not they want trade carts included in the counter value.