Contrary to most comments here, it is significant that other companies do. Facebook competes in the free market. If they scale back on data collection, that will hurt their offering to advertisers and cost them money that will go to Google and others. That lost revenue will harm their ability to retain talent and build new products, and ultimately cost them their user base. “We don’t track you” is not as compelling a feature as “free video chat across the globe.”

Facebook doesn’t operate in a vacuum. They can’t scale back data collection unless others do. Moreover, the United States doesn’t exist in a vacuum either. Scaling back all US companies will give a leg up to competitors in more lenient jurisdictions.