Again, I accept responsibilty for this issue and feel that perhaps plastic foundation is more the norm.
However, grooved top bars are used with wired foundation without hooks, not just for plastic foundation. Therefore, the drilled end bars are needed with this style frame if this type of foundation is used. As a result, I believe it is presumptous of them to assume that grooved top bars don't call for a need for holes in the end bars.
The bottom line is that it appears if you want drilled end bars, regardless of what frame you use, make sure you ask for them just to be on the safe side.