bitcoin safe in the transaction but if safe from corruption I think not necessarily. Thus it can be difficult to track if the bitcoin used for corruption. Perhaps some people assume are safe but it's about how Government policy only because corruption itself can through just about anything.
That is why we have the blockchain that we can use to track down the bitcoin address that has been use by the government officials and that will become the way for us to be sure that the corruption will be reduced because with the use of bitcoin technology then there will be more transparency and there is no chance for the officials to corrupt since anyone can look up to their address.
Why the government usually evade any feature of blockchain technology? Because they know use it will make them lose profit from corruption.