There are, I think, different norms and risk levels in different types of employment.
Somewhat ironically, it's much easier to get fired from a minimum wage fast food service job than it is to get fired from a six-figure-salary job at Google.
The expense and time required to hire a well-paid, highly qualified engineer is much bigger than to hire someone to do a burger-flipping job. Firing is writing off these expenses.
Your point aside, that particular example is not the best since it's a lot easier to quickly land a customer in the hospital as a random fast food worker than as a random software engineer.
That's the rationale, but most of the firings of fast food workers I've seen are not related to hygiene but rather due to scheduling and attendance issues. And very often because of management lack of planning.
It is not that easy, actually. There is remote possibility for it to happen, but it is not likely nor easy. You need to break quite a few rules and also be very unlucky too.
Somewhat ironically, it's much easier to get fired from a minimum wage fast food service job than it is to get fired from a six-figure-salary job at Google.