I could get a new set of screws and screwdrivers, but it's a lot more difficult and expensive than just using the Phillips stuff I have lying around. Depending on how important my project is (am I making a load-bearing shelf or am I putting up a poster frame?) the answer may differ.
Common in Canada, where they were invented. They're square head. Nearly impossible to strip, will stay on your driver with no support at almost any angle.
Not well known in the US because of a decision Ford made nearly 100 years ago to not pay Robertson the price he was asking.
Thus, to this day, any product that comes with screws is likely to come with Phillip's head, and all of its terrible downsides (I keep a supply of Robertson heads so that I never have to deal with Phillips' inherent shittyness).
Bad legacy decision making and inertia conspire to aggravate generations, long after the original thinking behind those decisions stopped making sense. The parallels to PHP are pretty clear.
(Of course every analogy holds only up to a certain point.)
The American bias towards towards the Phillips screwdriver has mostly to do with the gift of patent made to the government in order to support the war effort, putting them effectively into the public domain. They were better than flat screws/drivers, but that's not saying much: when I worked in aircraft maintenance, about half of all of the Phillips-head captive fasteners (Camlock or Dzus type) on inspection and access panels needed to be replaced between periodic (400-hour) major inspections due to stripped heads.