Guy was robbing him, you can see him finally get the knife out of his pants right before getting smashed
Can you imagine trying to rob someone and fumble fucking around for your weapon? LOL, the "armed" part is rather foundational to the practice of "armed robbery".
"Money or imma fuck you up good hombre! Uh... just give me a sec... got it!... wait... it's here somewhere... man, when you finally see this knife, you gonna be scared!"
Driver: "That's not a knife. THIS is a car."
Plot twist, the driver never saw the knife or noticed the robbery, and was just frustrated that the road was blocked