This question gets asked for every company. The way it works is that Amazon and Instacart. may copy. But walmart and target will be slow to respond. At some point, Amazon will be ahead in the game and Walmart is in a hurry to bring something similar to buy. Then they will acquire Bottomless

Another way, even if Amazon introduces it, they have to make $x billion from it to be viable. If Bottomless makes $100M per year from this funtionality, they are a good business. Meanwhile they can also rake up a few patents thus making forcing Amazon to pay some fees