Roads not upgraded when tile is purchased

[mmix2000]

Whenever roads get upgraded they happen on the entirety of civ territory. Also when a city expands into a tile that has old road, the road is properly upgraded. However if you purchase (for gold) a tile that has an old road, the road stays as old road until the next mass-upgrade by era advancement.

Attached is the image, I am in modern era and I purchased the tile with cofee several turns ago and it has not upgraded, its still classical and costs 1 movement.

 

[Corozivu]

I thought that roads got upgraded when a trade caravan used it in the new era not automatically.

 

[mmix2000]

Not when the territory gets expanded naturally.

It wouldn't make sense not to upgrade, all other roads get upgraded when the new era starts, even if not used by any trade route any more.