It is hard for them to make a tax since Bitcoin price is very volatile. There are many loopholes on this regulation because Bitcoin is not only a property it is in fact a currency where you can buy goods online.
Its the reason why bitcoin difficult to apply tax from government but if no tax then government will not so agree to legalize bitcoin.
This is the main reason of bitcoin or crypto loss in value. The government is followed by many people not to use crypto and caused crypto demand is low and of course the price is impacted.