To have $largeCompany buying their security suite where they can MITM on the proxy/appliance/gw/whatever without generating any alerts on the client side?
As far as I know, The US has almost non-existent privacy laws when it comes to what corporations are allowed to do/demand to do to their employees through contracts wrt. traffic on company equipment.
Forcefully and silently intercepting traffic on employee networks would AFAIK be illegal in most of Europe.