Why is mistake of fact usually not a defense to strict liability crimes?

According to the Model Penal Code, a mistake of law may be a defense if:

True or False, when performing external quality control one control is needed to verify patient samples can be ran.

Why doesn’t a broken speedometer serve as a valid defense for speeding?

How does the Model Penal Code treat a person who suspects the truth but avoids confirming it?

Which of the following is generally NOT a valid basis for a mistake of law defense?

True or False, Occupational Health and Safety Administration is ran by CLIA.

True or False, Class D fires require the use of a Class C extinguisher.

True or False, RBC counts performed on bronchoalveolar fluid should be diluted with sterile hypotonic saline. 

True or False, Clue cells are used as a diagnostic tool for bacterial vaginosis caused by Gardnerella vaginalis.