[Squid_Tamer]

While (relatively rare) left-hand exits are a thing in the US, I don't think that's what the arrows on this app is showing. The screenshot appears to be showing a single exit.

The arrows probably tell you whether your first turn will be a left or a right immediately after leaving the interstate. Many exits have two lanes, one for left turns and one for right turns onto the connected surface street. You have to know which exit lane you want to be in.

On a road trip, gas stations and fast food to the "right" of your travel direction on the interstate are slightly preferable because you don't have to wait for any left-turn signals. The US allows you to turn right at a red traffic light as well, saving even more time.