This headline might need some clarification. The client related costs are probably the most argued and most confused issue. Some (often customer) argue that the client should be cheap, while others (often vendors) argue that everything has its price.
superwise.net says that client hardware is allowed to have a low cost, while software should be free as far as possible.
Of cause the client hardware is not for free, but it should be cheap. This is due to the fact that no high tech components are needed. If you follow the rule about no vendor specific technology and only use standard components the price for a thin client should typically be half the price of an ordinary desktop computer.
The beauty of thin client solutions is that they eliminate a lot of installed software. This fact is of major concern for most software vendors, so they strive to find something else to charge for. A popular trend is to move the costs from the clients onto the server. By doing so they can still market their solutions as thin, since the clients are "for free". Instead the costs for the server software increase with the number of clients. This is just a marketing trick to avoid the fact that thin client solutions do not involve that much software. Furthermore, it confuses a lot of users, since the costs are not as low as expected.
There should be no such thing as client access licenses for OS or software, neither on the client nor on the server. The principles of client access licenses are that the costs increase with the number of clients. Depending on the purpose sometimes there are no free software available. In that case you need to pay a price for the server software, but this should be a fixed price not related to the number of clients served.
Due to the cost confusion mentioned above many users experience that despite the fact that they have chosen a thin client solution they still do not have control of the total cost. By obeying the simple rule No client related cost you gain 100 % cost control.
You also avoid confusing license policies that might surprise you some day.