The reason some people are not familiar with wage envelopes is because some countries do not use them. In the United States, for instance, many companies either use a normal envelope or pass out the pay by hand. There are two types of envelopes mainly used in the United States, plain mailing envelopes or mailing envelopes with a plastic view panel for the addressee. Both of these have disadvantages to using wage envelopes.
The disadvantages are primarily security issues. Wage envelopes have a place on the front for a lot of different information that only the employee would know while the plain mailing envelope doesn't. Of course, there is also tampering. A mailing envelope is not tamper proof. Many people know how to open a mailing envelope and then reseal it so no one is any wiser. Wage envelopes cannot be tampered in such a way. The security issues are a very good reason to consider switching to wage envelopes for your company.