Freakin' plumber

is making Jane freak out. This morning I went to take out the trash and I noticed that the Toto G-max fill valve was still in the Toto toilet box. Now that was surprising because the toilet had been flushed three times by the plumber before he left. I ran inside and opened up the tank and there was an ordinary Fieldmaster fill valve inside. Why? Why would anyone take a piece of equipment specifically designed to work with the toilet and replace it with some generic thing?
I rang Toto to see what would happen if we left the Fieldmaster in there and they said it would affect the fill rate and eventually the flow of the toilet. Great. I ordered the Toto is because the G-max has a great reputation and because all the plumbers like them. This plumber told me it was a "good" toilet. So once again why? I'll be asking him to explain and then install it as it was meant to be installed, but only when I've calmed down.