I assume that they do not have regular access to medical care, especially if they are immigrant workers.

Anecdotally, I have chronic kidney disease that would not have shown up on routine bloodwork / urinalysis. Only after multiple acute episodes did I get a biopsy for a diagnosis, and even that took a year of bouncing between specialists in a big city with good healthcare.

I get doing a blood panel once a year or so if you are not scraping by but never heard of doing a urine test without indication.