I would be happy if it is only for tracing my transactions, but with taxes? That would be a big hindrance with just little bitcoin earnings, And where would the taxes go? Since other countries did not legalize bitcoin some people who are using it still may get traced to where they are using but i still do not think that is also benefit for it will be a cause for lesser bitcoin oriented population. It will also discourage new participants to commit given that newbies or new participating members have very fair payout, if it gets tax decrease how do you think users will react. They might start wanting to be anonymous and hide their transactions by using other sites for receiving.