I’m the same way, except instead of making you feel bad about yourself, I will feel bad about myself for feeling so angry at you.
Then if I’m upset enough, I will become moderately less polite or, in even more extreme cases, drop any joviality from my voice and speak to you only in monotone.
Can’t speak with authority, but presumably FedEx employs packers and drivers; this person was probably speaking as a packer and referring to the truck they’re packing as “the truck.”