You have to first find the buttons, in the left menu (press “t” if it’s closed). Then, you can right click on the buttons and you will find an option to assign shortcuts.
Though, I don’t know for sure what will happen if you choose a key that’s already in use (I work with the Blender default keys and would rather not test overriding them).
Different 3D apps have different default behaviors for such common things, and it’s usually historical in “Why this way?” - because whomever originally coded it, liked it like that. A few thousand users later, now everyone is used to it.
Doesn’t mean it’s good nor bad (well, sometimes it’s actually good, or bad) - but nonetheless there’s the basic reason.