I don't get it
The icon is simply a graphical representation of a map. There is simply not enough room to show an on ramp or all the lanes of traffic on Hwy 280. I find that is does what it needs to do to convey the message, like this
. You wouldn't criticize that the mouth is too big and that eyebrows and nose are missing would you?
Another way to look at it, if you give someone directions to San Francisco, you may say, "go down this road and get on to 280 N." You may not say "get on to the on ramp for 280 N." The other person understands that you are being brief, like a person who looks at the aforementioned icon should understands that there is not much space to draw a detailed on ramp and 8 lanes of traffic, and that icon represents a map.
I think you are over analyzing it.