Why does LightRoom crop my images when I print 4x6s?

Why does LightRoom crop my images when I print? Why isn't it what you see is what you get? I just printed some 4x6s and they're cropped on all 4 sides? That doesn't even make sense. I guess I would understand if it needed to crop on two sides if the ratio out of the camera wasn't exactly 4x6 but why is it cropping all four sides?

I haven't printed a 4x6 in a while, but I seem to remember that if you print one on a larger size paper it prints as somewhat smaller than 4x6, as if it's leaving a border there. I believe that if you print on 4x6 paper at full bleed, you'd get a full 4x6.

But, I believe it's also common for a little cropping to take place. I don't know if it's Lightroom or the printing software.

It's the printer/driver, not lightroom. Some printers let you adjust this, others don't. Just learned this the hard way myself.