You should research what’s inside the boxes in Oregon before just assuming they’re easier to tamper with.

Doesn't look difficult: https://www.fbi.gov/wanted/seeking-info/ballot-box-fires (yes, that's in Oregon)

I’m not sure what’s so special in Oregon’s ballot boxes. But, tampering that is detected (don’t need much special to detect a burning box I guess!) is not a complete failure for a system. If any elections were close enough for a box to matter, they could have rerun them.