If you're in the left lane and being tailgated, then it's your fault, if there is no one in front of you.

If you're in the right lane and being tailgated, it's the fault of the tailgater.

There's a reason why some states have traffic signs that state "left lane for passing only".

It's always the fault of the tailgater. There are other ways to ask someone to move over like flashing your high beams. Tailgating just creates a dangerous situation.

I'm talking about the right lane.

And people tailgate in every lane when they feel you're going slow. Just with more frequency on the left lane.

And it's not like you can always choose. Highway lanes split in two all the time.

In my experience, if someone is tailgating you in the right lane, then speeding up is not likely to make them tailgate you any less, because such a person is either not paying attention or intentionally being a jerk.