You're right, we can't really know. But on HN, there are always a few comments to that effect whenever there's a larger discussion about EU consumer protections and anti-monopoly laws or penalties.
What % of the public holds these opinions? Who knows? Maybe someone will conduct a study one day, but 99.9% of internet opinions don't get studied, and 99.9% of people don't post mainly responsibly verified information.
There is so much to say about this, when most of our socialization has moved online. So much to be said.
I doubt it's very many, they just are very loud because there is a lot of money behind their complaints.