Unless you can control gomen, if not how you want to pass law based on your own opinion?

The problem is, the value of human being is very subjective. There is no fixed price on our heads, nor do we have specs like proton sagas do. If no one revealed their salary, it would be even worst, employers would be so afraid of overpaying that they lower their pay range instead to compensate,

How do they judge your value and decide how much you are worth?

Availability of your particular talent - It doesnt matter how much work you do, how much money you help the company earn. What matters is how many people else can do your job. Data entry people often work very hard, and help company earn money (no data entry = nothing come out), but they are paid so little because so many others can do the same job. If you dont want to do data entry for 2k, they can just hire the next person, or the next, or the next.

To be highly paid you need to distinguish and differentiate yourself from others. A special skill in a particular niche is the best. Best if no one knows what you are doing, how you do it, but that you must do it or company will fail, then you can demand XXXXXXX and goyang kaki.

This is why people work smart. If you data entry everyday boss wont appreciate it, if you do 1 mistake only also boss will marah. But your other "lazy" colleague everyday run around learning new stuff but not really doing his real work (data entry), so when boss got problem he know how to solve and also give boss credit for it. Guess who can get the promotion.

The point of job interview is too see whether or not you are suited to the post. Even if they want to offer you 20% increment fixed also need to see whether you are suited or not first what. Its actually better that they ask people to show their pay slip. Like that they have more information to make decision and pay people less (maybe its HR KPI) Then when you dont show, they will have more budget and can afford to pay you more! If everyone dont show and demand more, hiring budget always the same. So either everyone gets paid less, or they hire less people and you OT till 12am everyday.

Just because I have a budget of RM 2,000 doesnt meant I want to pay someone "perfect" for the job RM 2,000. That is why HR always have a range for a position, like RM 1,500 to Rm 2,500.

Maybe I meet a worker A who has perfect pointer, prior work experience (impressive previous work resume), smooth talker, polite, convincing, I would surely like to offer him the highest range of my budget RM 2,500 to try and attract him.

Then I meet a worker B who isnt that good, so i offer him RM 1,500.

Both will be able to do that job, becos my company so stronk that sales automatically keep rolling in bla bla bla, But worker A obviously has the capability to maybe even exceed my expectations, or have the potential to rise in my company. While I feel worker B does not have such potential. Yes, both can do the entry level job I am advertising for RM 2,000. But human beings have different capacity, and so I lowball B in order to have the budget to hire A.

Asking for payslip is just part of my evaluation, like many have already said in this thread, it IS NOT MANDATORY for you to show it, but employer IS ALLOWED to ask for it. It is up to you whether you want to give or not. There is no right or wrong here. Saying the employer is wrong to ask for it (unethical/lowballing) is false. Payslip reflects a persons value quite accurately, especially the longer you work.

Going back to my example:

Let say I ask for worker A's payslip and I notice that his pay always around RM 1,000 to RM 1,500 for the past 10 years, while job hopping around. Suddenly I might have to rethink my evaluation. Why was he always paid so low? Was there a problem in his previous company? Has he perfected the art of interviewing after 10 years and is trying to con me now?

Then worker B refuse to give and I immediately hire worker C, who just come in, roughly same standard as worker B and is willing to show his payslip.

Clearly, whether or not you show your payslip is up to you, and can be good or bad depending on the circumstances. It is part of your evaluation, and is another form of the question "tell me more about yourself". You can tell them, or you can choose NOT to tell them. Problem is when you choose not to tell them, what will they think?

Bottom line:

Employer is RIGHT and SHOULD ask for your payslip. You CAN CHOOSE whether you want to give or not.

In most circumstances, showing your payslip means you are on the losing end of negotiations, but please also consider what you lose by choosing not to show your payslip. Right or wrong, it all depends on the circumstances and how you handle the situation.