I calculate percentages every day. Turns out yesterday the guy in charge of the company I worked for asked me the formula to work out the % difference between 2 numbers. He didn't ask because he is stupid or has no capacity to do Math. He asked because it has literally been years since he has been required to do it.
Similarly, if you ask me what an onomatopoeia is. I learned it in school and I know the word exists but I haven't been asked to define its meaning for so long that I have forgotten. Now I come to think of it, it might be a word that sounds like another word? Anyway, the point is if you do not practice or recap these things you forget.
4 years ago I passed the Cisco CCNA. I haven't touched a router or switch since. If you asked me anything about networking I would look at you with a blank expression and then answer it with 'Google it?'
Now.. failing a 10th grade Math exam then saying that the tests are too hard or not relevant to daily life is ridiculous. Some of this stuff may not be relevant to your daily life but in general a lot of jobs and general task's in day to day life touch on the key Math skills you learned in school.
School should provide you with a firm foundation in key subjects. If 5 years later you have forgotten 70% of what you learned in science because your job doesn't involve this knowledge and you have no interest in reading / keeping up with science in general it doesn't matter. The chances are you will have remembered 90% of what you learned in English and 80% of what you learned in Math because these you depend on to complete your work.
It doesn't matter that a board member completely flunked a Math exam. It doesn't make him stupid. What is worrying is the attitude the educator takes to his failure. The best response is 'wow compared to these kids I am really rusty at Math.' The worst response is 'my math skills are OK, this test is irrelevant to day to day life.' It undermines teachers and tells kids it is OK to be terrible Math. (If the kid has aspirations to be a school board member this may be true but for a million other jobs and situations it certainly isn't.)