Precisely. Recruiters ask to ensure that there is at least a "ballpark" match up before proceeding -- it would be a waste of your and the hiring team's time to interview you if your salary requirements are outside of their budget.

I can understand how some may be hesitant to offer this info up since it is considered sensitive in many cultures, but I have no problem doing so. I understand that there is no malicious or malevolent intent in their request for this info (at least, there rarely is...).

My understanding of the "never tell them your current salary" advice is that it's less cultural and more "they can use it against you to pay you less than you're worth". It's a negotiation, and "never give the first number" isn't for culture/privacy.

In some cases I can understand its a way of verifying employment, however as far as salary negotiations, i'm told it's basically poker, and if you show first, they are in charge.

not if your current number is way above market. it's also not at all like poker in that lying is not an advisable way to try to win. (never lie about salary, or anything else, to a prospective employer.)

One of the cases I've seen they actually wanted a copy of the pay stub. Which I found a bit frustrating.

You should tell them your total comp including benefits. Don't overlook the value of benefits.

At my last job for every hour I worked over my standard 40 hours I got an extra hour of annual leave. Standard hours in my field tends to be at least 45/wk so when I switched jobs I quoted a figure that included the value of this extra leave.