While the answer should be clear to most people if they read the actual news, not all the specific details might be at one's fingertips. And so, heading into the hearings, I thought I'd post an answer that one can use as a sort of "tip sheet," should it come up at any gatherings without "outraged" process Republicans.
And we'll start with the short, but none-the-less proper reply --
Because there is absolutely no evidence that either of them did anything illegal. Nothing.
But for those who like to have actual specifics:
When Joe Biden got the corrupt Ukraine prosecutor Viktor Shokin fired -- a) it was on order from the U.S. president, b) it was what European nations wanted, and c) it was because the corrupt Ukraine prosecutor was NOT investigating the Burisma oli company. The point of Biden's action was to bring in a new prosecutor who WOULD investigate Burisma -- the company his son was on the Board of!
AND -- it *has been investigated*!! The new Ukraine prosecutor Yuriy Lutsenko then *re-opened* the investigation. And nothing illegal was found by the Bidens. And the U.K. also had a banking investigation. And nothing illegal was found by the Bidens.
It has been investigated. Twice. And no wrongdoing was found by the Bidens. None.
The idea of Ukraine attacking the U.S. is disinformation by Russia. It's an attempt to tarnish innocent people and affect a U.S. presidential election. Again. On the other hand, trying to extort, shakedown and bribe a foreign government to affect a U.S. election is a crime. And impeachable.
And further, as the bottom line: if the U.S. Justice Department actually, really, truly thought there was the possibility that the Bidens did anything illegal...THEY would have opened an investigation years ago. And they didn't. And haven't. Because there is nothing.
That's why. I hope it's clear.