Increase in wages, perhaps no. Not for SCEA (which I am yet to pass), but from my experience in passing PMP at own expense (my organisation didn't reimburse me as I was not at "Manager" level or above), a senior leadership person convinced me during appraisal discussions that "it was a waste of money, and that I should have asked him before going for it". So I don't see that our bosses will appreciate it, but yes I do get the respect from fellow project management practitioners, who realize the value of the certification and the effort involved in completing it. Certification thus, for me, is possibly a matter for great personal achievement, it makes me feel worthwhile and competitive.
In the company for which i work, wage policy by productivity and/or by goals. These goals are reviewed semi annually.
If the employee and the manager have consent that a specific certification (and the knowledge obtained to get it) would be valuable for both, there would be an increase.
Otherwise, the company not even pay the vouchers required.