Right, the 80% failure rate is entirely because nobody failing could manage a taco stand. It couldn't be because of entrenched competition and that there simply isn't enough consumption to support that many businesses.
That is a failure of management. Business decisions like where to put the taco stand are the absolute most important thing any management does. Stupid ones that cause a business to fail are almost certainly caused by bad management.
There is no such thing as unskilled labor. The skill doesn't come from the labor or base education required it comes from the individual performing it. In high school I worked in a McDonalds, there were individuals who could produce 4-6x as much output in the same time frame as their co-workers. They might have been "flipping burgers" but they were skilled at it and the difficulty rating of performing that job at that level by far exceeds anything being done by management in the store both mentally and physically.
The hell there isn't. Anything that can be learned in an afternoon is not a skill. Nobody gives a damn if you're 20x more efficient at flipping a burger. It won't make a difference to anyone but the person who's being efficient. A manager who can make his store 20x more efficient in the numbers that actually matter is a fiscal God and will be rapidly promoted.
Let's be real clear here. What matters in business is making money. First, last, and only. If your job can be done with minimal training by a highschool kid for minimum wage, it should be. Anyone demanding more is a greedy fuck of a fool but doing his job poorly will probably not cost an entire shop to close down.
The same is not true for management. You get a bad manager in and everyone may very well lose their job because the shop gets closed. Most managers are not espeically good though, which is why they are managing a McDonalds instead of a region of them.