Regardless of what the financial markets value them at, their resources are proportional to profits, not market cap. That aside, they also have lots of product

Regardless of what the financial markets value them at, their resources are proportional to profits, not market cap. That aside, they also have lots of products and teams and some have more budget and resources than others. Saving some memory usage in teams for more than double the development costs, is probably an unattractive position for that team. It also makes it hard to keep features consistent across platforms (as it is, teams struggles with that!)