Part of good Q&A is focusing on a single question, so that when potential answerers look at your question, they don't get confused and give you an answer to the question that you weren't expecting. It also ensures that good content can be voted to the top, since all answerers would be answering the same question.
With that said, here is the part of your question that I read in the body of your post, the part that I specifically addressed:
how do you go about minimizing the risks of giving out your tax ID?
My answer to this question was:
Now, if you're doing work for a larger client, they may very well want your tax id in advance. In the United States, you can go to the IRS Website and apply for an EIN Federal Tax ID, which means you don't have to give your personal social security number to clients who contract with you.
If that's not an option, just do some basic research on the client. If they're well-established, they likely have a website, some reviews, public artifacts on the Internet that verify that they exist and are indeed legitimate. If something doesn't feel right, move on and find another client.
Perhaps I could have made it more clear that using an EIN is safer than using an SSN, and this is how I get around this issue. I'm just not as protective of my EIN as I am my SSN. I suspect there was some confusion on your part, as well as mine, by assuming that you're in the United States and that by "tax id" you meant "social security number".
In my defense, you did make significant changes to your question after the fact, and then you left a comment under my post, in which I responded that I'd take a look when I got time, which hopefully will be this weekend. :)
In your defense, I did miss the title of your question, which just happens to be different than the question you posted at the end of the post body. Hence, I hope you understand my confusion. The post title is meant to draw in the reader, and as a fallable human, I tend to focus on the nitty gritty post body, and the questions it contains, when addressing an asker. This is why I usually suggest that askers put the question in both the title as well as the post body -- so it's clear.
In conclusion, I don't think you're totally off base here in your question. We don't want this to become a discussion forum, and we want people to be satisfied with the answers they get. But we also must realize that for that to happen, questions must be focused, definitive, and crystal clear. Hope this helps! :)