It would be relatively easy for them to take this data and search the databases that it has been revealed that they have access to in the past, such as those from major companies, as well as from the internet. Though they could do the same when people register for tickets or give ID. Then, simply by entering an area where they have cameras set, or trying to leave the country, they could have all of your data scanned, and flag you for extra questions, because you happened to write a post on Facebook or wherever that suggests maybe you have anti-government views. This wouldn't even have to be revealed to the people using such a system, as they'd just be told to hold you for questioning or some such.

Local authorities could do the same if they wanted to, or even just use technology to track devices. They could check what devices were in the area when something happened, and just slowly pick them all up and harass them, until they find whoever they are looking for.

It's important that we pass laws limiting such things, because they actually are pushing and trying to get us into a scary police state that makes 1984 look tame by comparison.

It's getting to the point where it might be better for some people to just leave the country via the very few ways left that have lower security, before it gets even worse.