zehavasdad — I don’t know where you have worked, but MANY non-Jewish employers are closed on non-Jewish holidays and do NOT pay their hourly employees for those days. Generally speaking my experience has been that hourly employees are never payed for days that the employer is closed unless they have some sort of vacation day deal in place. If there was no deal in place, your friend’s experience is pretty acceptable in the general world. If there was a deal (spoken or otherwise), that is a totally different issue that has nothing to do with Chol Hamoed. . .
For example my sister worked in the office of a non-Jewish company, and they were closed for many non-Jewish and legal holidays. She did NOT get payed for those days, but had the option to use them as part of her vacation time. Since she needed her vacation time (it was not many days per year) for the Jewish holidays she always lost pay on the non-Jewish hoidays.
My sister-in-law also worked for a non-Jewish company. Their policy was slightly different. They required you to use the week of Dec. 25, when they were closed, as part of your vacation days, even though they were closed. So if your deal with them included 20 “vacation days”, it really was only 15, as they counted that week against your deal.
As a previous poster said, the point is that hourly employees are exactly that — paid for by the hour that they work, whether the not working is by their choice or by the choice of the employer. (I do think it would have been more appropriate business protocol to inform the employees when they were hired as to which days they would not be working, so they can plan accordingly, but that is a side point.)