I don't think these rates are new housing. You're looking at the real estate market as a whole. There's no way 25% of China's GDP is new housing, or Canada high teens. As real estate as a whole climbs as a percent of GDP you expect to see more NIMBYism because it means people have even more of their wealth tied into their homes, and more reason to not want competition. Which, economists seem to agree, is exactly what has happened in Canada.

Canada is only a country of 38 million and they are expected to take in 1 million migrants this year, all of whom don't bring a home with them. They took in half that last year. Their population is growing much faster than ours, but new housing starts are only around a quarter million per year.

I don't assume they are correct just because they are in wide agreement which is why I'm asking what you know that I (or they) don't. The total percent of GDP from the real estate market doesn't indicate much other than that houses are unsustainably expensive.