I have heard that many of those screws that appear to have both a long slot and Philips style plus shape, are actually designed to also accept Robertson, and that in so doing using a Philips driver on those screws has a much greater chance of damaging the screwhead. These are often seen on things like outlets and light switches.
(Note, many but not all are designed to accept a Philips driver, with a visible cross that slightly extends past the 45 degree angled robertson opening, plus having some visible slopes to the edges rather than near 90 degree edges that a screw deigned for only slotted or Robertson would be expected to have. But there are some that are strictly flat and Robertson only).
For those particular screws the best bit is allegedly the ECX bit, which is basically a Robertson Flathead combo bit, and the second best bit to use is the appropriate sized Robertson bit, with Flathead next, and Philips being best avoided.
This makes including a Robertson driver actually not too unreasonable. I in the US have plenty of switches and outlets could be driven with it.