Mixed responses...but err on the side of not being a Usholeeee..

For a start, in Europe anybody can ask an employer/previous employer to reveal the salary details of one of their employees, but unless the individual concern has signed an agreement to release that information the employer would be braking the law if they release the information.

Of course in Thailand there is little or no protection of personal data.

That aside, I think you are getting distracted by pennies.

You have a candidate in front of you with a great resume who you presumably wish to hire.

Offer her what you think she is worth to your business.

Don't know which "Europe" you are referring to but in Sweden anyone can call the "swedish IRS" and ask how much person X taxed income was last year and from that it's not very hard to figure out their monthly salary. And you can sign a million "agreements" about prevention of releasing information about salary to no avail as it will anyway end up as "offentliga handlingar" (roughly means "public documents") when you do your taxes in Sweden.