I can tell you with certainty that this is not a universal practice
In some jurisdictions profits earned on currency exchange operations are not taxable, and its official. Further, if Bitcoin is treated like property (or property rights), you may look for tax exemption. Again, in many jurisdictions if you held some property for longer than one year (in some parts of the world longer than three years on expensive items like houses or apartments), you don't have to pay a capital gains tax. Technically, you still have to pay it but you receive a tax deduction which equals the price at which you sold this property, so effectively you don't pay this tax
If you have been selling Bitcoin and haven't reported anything to the tax agency I would suggest consulting a tax attorney or something before landing yourself in hot water
I don't need that. My tax service officially declared that they have nothing to do with Bitcoin
Which jurisdictions are that? Bitcoin is not regulated here but I found out that it is taxable because they added an addendum to the tax law for Bitcoin particularly and that change wasn't officially declared either.