Washington State has voted entirely by mail since 2010. Is there any evidence its elections are especially rife with fraud?

Someone points out that there is still an in-person voting option available in each county. But by 2010, all counties had adopted vote-by-mail

The current Secretary of State is a Republican, having won statewide twice during the period of universal mail-in voting

And a Republican just won a House seat in Los Angeles County, in an election that was conducted almost entirely by mail-in voting. The widespread Republican hostility to this method of voting doesn't seem quite logical to me, even on purely strategic, self-interested grounds

For instance my grandpa definitely would've voted for Trump in 2016, but he's old and no one took him to the polling site, so he didn't end up voting. (I was away at the time!) If he was sent a ballot in the mail, I'm pretty sure he would've voted