When I worked for the government I wanted to scrape some publicly available data from the web. Because the data involved information about people I had to write up a document explaining exactly what I was using the data for, exactly what information I would be collecting and why it was necessary, explain where the data was to be stored, and most importantly specify exactly how long I needed the data and when and how it would be safely removed. This had to be approved by a privacy officer.
I was shocked, because this is data that I, as a private citizen, could easily scrape. I asked why I had to do something so involved for a project I could easily do in my spare time. The answer I got was this: Because the government has extra authority they also have extra responsibility. As government employees we have more power to impact people's lives so it is our responsibility to be very explicit is what we do and why we are doing in.
In ad-tech there are oceans of data that are not publicly available, and in the US virtually zero restriction who looks at that data and what they can do with it. I've watched people move around town via trackers when the use they web, seen where they got coffee and seen which doctor they go to. I used this information to demonstrate to the legal team at previous company to care about user privacy. They were shocked but in the end made no real policy decision. Some of the big players likely have tighter security but only for business/PR reasons. I can assure you that a random data engineer at a mid-sized tech company has far more access to your personal secrets than an FBI agent.
Don't get me wrong, there are agencies in the government that have more surveillance power than they should and it is ripe for abuse. But don't think "it's not big tech", especially since there is a ultimately a thin line between big tech and big govt.