Businesses choose to send this data to the ad platforms for their own benefits - better targeting, measurement, and ML optimization of their ad campaigns.
The businesses are legally accountable for the data they're sending and complying with privacy laws, but to most platforms it's a dumb pipe for whatever data the business chooses to send.
The businesses are legally accountable for the data they're sending and complying with privacy laws, but to most platforms it's a dumb pipe for whatever data the business chooses to send.