The issue is that this is essentially impossible. First of all, any team can say "we treat all our drivers equally" and then continue preferring one driver. And McLarens call to stay out shows exactly why you can't keep things equal. The correct option would've been to call both Piastri and Norris in because that was the optimal strategy (which is why every other team made the same call) but the reason they didn't call them in was because they didn't want to compromise Norris with the double stack. The call to pit wouldn't have been fair to Norris but not calling them in wasn't fair to Piastri. Whether McLaren wanted or not they ended up with a call that benefited one driver over the other. They couldn't have treated both drivers equally even if they wanted to.

The only way drivers could even be considered as being treated "equally" is if the team chooses to back a driver on a race to race basis. If one driver is doing a better job / gets more lucky throughout the weekend then they get preferential treatment. And I think that's how we've come to the number 1 and number 2 drivers. One driver simply does better than the other. That just gets extended to the WDC where if one driver has been consistently better than the other driver they get more backing to make sure there's a chance to get the WDC. In an effort to keep things always equal you end up mistreating both drivers and leave the WDC to be snatched from the jaws of victory.