Making money and complying with the law. They are obligated to do both. In many countries laws are still enforced.

Protecting their app store revenues from competition exposes them to scrutiny from competition regulators and might be counter productive.

Many governments are moving towards requiring tech companies to enforce verification of users and limit access to some types of software and services or impose conditions requiring software to limit certain features such as end to end encryption. Some prominent people in big tech believe very strongly in a surveillance state and we are seeing a lot of buy in across the political spectrum, possibly due to industry lobbying efforts. Allowing people to install unapproved software limits the effectiveness of surveillance technologies and the revenues of those selling them. If legal compliance risks are pushing this then it is a job for voters, not Google to fix.

Complying with the law is just another way of protecting your money. I have no doubt if they would break laws if they judged it better for the bottom line --- in fact I have little doubt they're already doing so. On the flip side, if there were ruinous penalties for their anticompetitive behaviors (i.e., in the tens or hundreds of billions of dollars) they might change course.

Certainly voters need to have their say, but often their message is muffled by the layers of political and administrative material it passes through.