People who don't know how to keep left.
This person was doing 70 in the right hand lane of the tunnel.
Now this itself is not illegal, but once in the 100 zone she elected
to continue to "fail to keep left". And in a 100 zone it is illegal. Duh.
Once you have diven in europe where people do keep left you really
notice how much it screws the flow up. This woman is clearly
on her own, in the right lane with no reason.