There are so many ways of hiding the destination of the scammers coins that it is virtually impossible to trace it. A lot of sites on the internet will allow you to register without KYC/AML requirements and you can push those coins through these services. They also allow you to change the sender address, to withdraw from their services and some even mix your coins.
A lot of these sites goes down and then resurface under a new domain, so you cannot trace any logs, because they are destroyed or not even logged by these sites. A lot of people open multiple accounts, which makes this even more difficult to follow.
False. This may have been the case back in the Silk Road days but Bitcoin can definitely be traced now. This is why many deep web markets have switched over to Monero.
If you ONLY deal from bitcoin to bitcoin it is possible to remain anonymous... the problem is that most people, at some point, buy bitcoin with fiat. If the government/someone really wanted to track down a transaction, they can do so even through bitcoin mixers and whatnot.