You might not yet realize. The construction worker is a female.

I had seen female bus drivers and female taxi drivers, but not construction workers. Only recently have I found many once masculine jobs are shifted and now carried out by women.

Where are the guys? All gone to China for business? Maybe.
The sad truth is many men went to China for business initially, and started another family in China, leaving their wives and children in Hong Kong.
Not all, but many as far as I know.
What's this used to be? Hong Kong men would leave their wives in New Territories like Tuen Mun, Yuen Long, and Sheung Shui and claimed that they needed to do business in the commercial district - Kowloon. They were successful in nesting second or even third family elsewhere.
Illegal, but was generally well accepted. It makes me think of my mom who has experienced this kind of social unfairness, ... tears almost dropping down here.
As the Chinese say, "Old Wine New Container" to describe "Nothing New Under The Sun". These stories will just go on and on, endlessly.