During your mobilised service you are paid as per your civilian earnings before mobilisation. Wasn't always thus, but is now. What sometimes gets missed is the effect before and after. Service in the reserves is not always seen in a positive light by employers, and may well act against you in terms of promotion (if employed) and has an impact on the time you can commit to your own business (if self employed).
After mobilisation, you will probably be disadvantaged again as others would have progressed through demonstrating their loyalty to their primary employer, or targeted your clients while you are away.
All of this is known, and accepted, by reservists. Dealing with the effects of mobilisation (whether true voluntary or volunteer to be compulsorily mobilised) to meet a clearly defined capability gap or in case of national emergency is one thing. Being asked to do the same just to prove a point or "equal misery for all" is another matter entirely.