The reason they teach biology before they teach chemistry in high school is that biology was invented first. Even though you need chemistry to do biology, but not vice versa.
The reason that you have a water bubbler in your office is that it used to be difficult to filter water effectively.
The reason that Blockbuster exists is that VCR tapes used to cost more than $100.
The reason that SUVs have a truck chassis is that the government regulates vehicles with a truck chassis differently.
The reason you have a front lawn is to demonstrate to your friends and neighbors how much time and energy you're prepared to waste.
The reason the typewriter keyboard is in a weird order is that original typewriters jammed, and they needed to rearrange the letters to keep common letters far apart.
The reason we don't have school in the summer is so our kids can help with farmwork. Or because it's too hot and there's no air conditioning...
The reason there's a toll on that bridge but not on that road is that there used to be a ferry on that river, and the ferryman needed to make a living.
The reason you go to a building to go to work every day is that steam or water power used to turn a giant winch-like structure that went right through the factory building. Every workman used that power to do his work. As factories got more sophisticated, it remained efficient to move the workers, not the stuff.
What's your reason?