ELI5 Trucks - why do European trucks look different to US trucks?

Why do European trucks have their engine below the driver compared to US trucks which have the engine in front of the driver? What are the weightstations on US interstates used for? Is Optimus Prime European or American? ... we explain like I'm five Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: shaaeft, sgrumpy, holyhand_grenade, missionred, krimin, sliceoflife and serath62 To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter: https://www.twitter.com/eli5ThePodcast/ or send us an e-mail: ELI5ThePodcast@gmail.com