If builders and owners were equally concerned with health and safety as they are with profit, there would be fewer "heavy handed...restrictions" and the construction industry would be allowed to self-regulate. 

Given that they have lived in the unit for over 10 years and their mother lives there as well, this option may not work though because of the following RSO guideline:"If a tenant lives in an eligible unit but has continuously resided in the unit for at least ten years, and is either 62 years old or older, or is disabled as defined in Title 42 United States Code Section 423, or is handicapped as defined in Section 50072 of the California Health and Safety Code, the tenant is protected and the landlord cannot evict for an owner, relative, or resident manager move-in."

Health insurance8. 

@Pete M.Hey Pete, I’m local and have houses in Frasyer, it is street by street on areas, I will say how big or small the apartment is will make a difference too. The

So today the tenant moved in a 15 lb dog that's old and has health problems.

As a follow on, Congress did not extend:https://apnews.com/article/joe-biden-business-health-coronavirus-pandemic-us-supreme-court-65d530199d4dd2c99b9839fcd9c22294WASHINGTON (AP) — A nationwide eviction moratorium is set to expire Saturday after President Joe Biden and Democrats in Congress worked furiously but ultimately failed to align on a long-shot strategy to prevent millions of Americans from being forced from their homes during a COVID-19 surge.

My sister is a health freak and my mother is 93-years old.

"Because it is a big investment and you really rely on it for your overall financial health"Maybe drop a vague hint about you hating to look for a new tenant......

Obviously health benefits and tax payments are factors.

It's expensive for a landlord to turnover, they may be liable for some of those health hazards you listed.