In that case why don't they also take into account (in the case of spouse visa) the earnings capability of the Filipina, since they are permitted to work from day one ?

Why don't they allow her to submit a written offer of employment ?
Are they assuming that she is to be a 'kept woman', with no financial contribution to the joint kitty ? That is clear discrimination.

Also, your PAYE tax deductions are estimated partly from calculated FUTURE earnings...not on what you've earned that week or month.

The whole scheme is flawed and clearly unfair and discriminatory.