i doubt the government is spending the money and resources just to spy on regular people and watching what they do with bitcoin.
Why not? It's pretty interesting and easy for them. I mean they don't have it that easy with fiat. They can't follow it around so easy but they can follow bitcoins.
An i think they know bitcoins potential. They would be stupid not to take care. In fact i know they are not stupid since, i believe gavin did that, some years ago he held a meeting with the CIA that wanted to get informed about that new currency. Surely they will track.
And you say they don't care about the normal user. Why not? It is so easy and so few data... and if it is easy then they will observe it. Just in case.
If they will use that data to blame you against IRS, that is doubtable.
Most of these agencies work isn't to spy ordinary citizens, they try to spy other agencies and governments so the USA can have the upper hand.