Is this "we can't drive" day??

How about when you try to merge onto the highway, and someone is in the right lane and you watch for them to pass by while you coast on the on ramp. They keep slowing down thinking you'll pull out in front of them (like you aren't supposed to do) You wait for them to drive by, but they don't. As you start running out of on ramp, they keep slowing down in the right lane. They don't drive by, get into the left lane, or let you on, they just keep slowing down.

It's as if they are yielding for me, when I am waiting to yield onto the highway.
What's worse is when you are behind someone doing 55 and they slow down to allow a car on the highway.

Back in the time when drivers Ed was taught and people actually knew how to drive, you were instructed to always accelerate into the open spot when changing lanes and adjust your speed with the flow of traffic after the merge. You were instructed NOT to slow down, and thereby force the traffic you were merging with to slow down.
It is always the job of the merging driver to look ahead and adjust his speed to enable his car entry into the open space. Merging in smoothly and allowing the traffic being merged with to maintain a steady speed is as much yielding as slowing or stopping to let them pass. Anytime you disrupt the flow of traffic in a lane, you are increasing the possibility of an accident.