I think there are some heavy generalizations in this thread.  I have worked in pretty much most of the GCC countries and also in other parts of the world at senior management levels so I will try to give an overall perspective here.
What's different in KSA (And other GCC countries) vs. the rest of the world:
1) The number of expats - most of the GCC countries do NOT have a skilled labor force to cover all the jobs that are available. This means that they bring in a LOT of expats vs. say other countries e.g. in Europe. Over time, this has led to a big shift in population demographics e.g. in UAE, 80% are expats; in Bahrain, 50% etc etc. This is quite unique to this part of the world
2) With the shift in the population demographics, there is a BIG fear of losing cultural identity as expats out number locals in some countries. So what happens? the kafala system to maintain control, no naturalization or citizenship etc
3) The economies here are heavily dependent on oil. When the oil price was high, the local population got a lot of subsidies and support from the government. With oil prices at a low level for many years; the subsidies are being cut, non oil revenue is being explored and the push is to move locals into employment
The above are the facts as at today.
So what does this mean as far as this thread goes:
1) Based on your skill set and level (seniority), you CAN negotiate. Again note that this depends on your transferable SKILLS e.g. if you are a showroom sales person or entry level accountant or a data operator, you won't have any room to negotiate as they can easily find people at your level and with your skills, much cheaper. If you are an avionics engineer specialized in specific technology or a CFO for an investment bank or a scientist working on pharma developmental products; of course you will have a stronger case to negotiate. Simple market supply and demand people!
2) Recruitment in such an economic situation, is ALWAYS preferred through networking and references. Why would a company pay extra to an agency to find candidates (Especially junior ones) when they have dozens of CVs being handed to them everyday?  and at senior levels, they may get an agency as candidates with specific skill sets are difficult to find - again supply and demand choices. And there is nothing wrong in this; I have experienced recruitment through references (qualified candidates of course) in UAE, Singapore, Hong Kong, UK, Malaysia, Germany etc etc. This is NOT just a Saudi phenomenon
3) Your rights and work experience WILL vary depending on the type of company you join. Big reputable companies and multinationals generally treat their employees better and don't abuse the kafala system. Smaller companies do. Again, you cannot generalize here but instead be careful in your choices. In my 10 years in the GCC, I have been offered jobs many times by companies who offered to double my salary but I refused after assessing the company reputation and image. Money is not everything