take it like as if youre on a travelator and you are walking forwards while the travelator is also moving forwards. so if you take the speed of the travelator plus the speed at which you are walking ON the travelator, your speed would be greater than the travelator’s. but when you stand still on a travelator, you move ALONG with it, causing your speed to be the same as the travelator. so when you walk forwards, youre adding on to your initial speed which is that of the travelator. all of this applies to what the meme is saying as well.