The reason all athletes don't wear the same shoes is nothing to do with the shoes. It's the millions of dollars the shoe companies pay them to wear the shoes.
In passing, regrettably running shoes have reached the stage where they are assisting the propulsion process. This must be clamped down on. Hard. More than 100 years ago high jumpers started wearing shoes with springs in and this was soon outlawed. Don't even talk about the 'blades' used by amputees, that took Oscar Pistorius, a club level athlete, to an Olympic final.