So I say this based on personal experience. The Siemens' sales force uses their size and influence (especially with existing customers) to absolutely screw over customers and smaller competitors with better products. Siemens is no different than many other big companies who can use all sorts of unethical (but legal) tactics to sell.
It's very possible to work as an engineer in a big company and have zero idea as to what everybody else is doing to screw people over.