You can hide your money, but you can't hide your spending. If someone is living beyond their means, it's a signal to IRS or (place name of agency that taxes you) that you are worth their effort.
Also, government is not the only one who is abusing power. Rich and powerful also do that. Bitcoin can at least prevent some of that abuse by being censorship resistant.
This book's author claims it is the third largest business(money laundering): http://www.amazon.com/The-Laundrymen-Laundering-Largest-Busi...
There is also a matter of complex tax codes. Today they predominantly used by large businesses and wealthy people. With Bitcoin as a very democratic tax evasion / money laundering mechanism, is there any chance that we will see clear and simple tax codes in Bitcoin future?
Does it really? Bitcoin by design records every transaction forever globally.
The only reason it would be easier that it is easier to program compared to banking APIs. I am not convinced by stuff like Darksend [0] so far.
http://www.newsbtc.com/2015/01/01/mt-gox-bitcoin-theft-insid...
While Bitcoin came out of our "own" community, and a lot of technologically inclined people are enthusiastic over it and it's features, I wonder if Bitcoin got planet-wide adoption, would it be a bigger boon to the man in the street or the big fat rich cats? It makes hiding money a lot easier (akin to the Swiss bank account but with less trouble transferring) and makes it a lot easier for money to "disappear" and be impossible to take back.
These things strike me as things the man in the street wouldn't care so much for (the government tracks his income so he can't whisk Bitcoins away, and working black is, well, like working black for dollar bills, not that different).