It's not the 20th century anymore. China's per capita emissions are higher than you're letting on. Higher than some European countries.
[1] https://en.wikipedia.org/wiki/List_of_countries_by_carbon_di...
This infrastructure uses a lot of steel and concrete. It is not just an input for export goods - they are places for people to live.
Given that infrastructure building has set commodity prices for a decade, it wild be surprising if it wasn't the main part of thier emissions.
We can't begrudge Chinese, Indian and African people a modern way of life. Building that stuff emissions carbon. Its a difficult problem.
In a way trying to call a Chinese freeway an input emission for westbound exports is a moral cop-out.