I wouldn't say this is always true. Numerous times I've bought digital games from the PS store that were heavily discounted while places like Gamestop were still asking MSRP ($69.99) for new or $10 off for used on a game that came out years prior. I still prefer to own a disc but sometimes digital is cheaper and more convenient.

That's why stuff like Gamepass are picking up. Poorer families may not be able to afford a £70 game each month, but £15 a month for a huge library is more achiveable.