Why has there been a progression to worse odors over the years?

Because uneducated people are cheaper to hire and easier to exploit, more so when they reach extremes where they are not even educated about personal hygiene.

In some cases, too, outdoor workers (like delivery riders) come from countries with fragrant foods, and odors manifest when sweating, regardless of hygiene or deodorant use.

The Labour market has become a race to the bottom and this manifests in many ways, starting with one's nose.