In the linked post, I give some detail on the situation and the scams.

The legal scam: your travel agent or ticket seller gives a you a convenient form to take your details and apply for your electronic travel authorisation on your behalf. You might then later discover you were charged over $100 for their convenient form, when you could have paid $20 by going direct to the gov website.

The illegal scam: some 3rd party websites claim to walk you through getting a travel authorisation, and they of course charge you. But then they do nothing… they never actually file an ETA for you. They just take your money.