[mbreese]

What you’re talking about is a different form of evolution where there are effectively “multiple answers to the same problem”. A common example is if there are two bird species eat the same nut, they might have two very different beak shapes that both open that nut.

But that’s not how the type of evolution in a single virus works[0]. Within a single organism/virus, the evolution is more like finding a local minima. There certainly could be a more effective design with a different shape. But it is very difficult to break out of a local minima through mutation and natural selection. You still have to maintain the function of a protein while simultaneously mutating it. So, breaking out of a local minima is really difficult. As you said, evolution is a slow process, so you wouldn’t expect to see dramatic changes in a shape and keep the same function.

[0] I’ve deliberately left out things like horizontal gene transfer, transposons, and gene duplication, all of which can involve hyper mutation or gain of function without being under selective pressure.