Why high-end cable manufacturers don't post measurements?

That is a poor question because some manufacturers do state some measurements.

What measurements are you looking for ? The trouble is no set of measurements directly tells the consumer how well the cable will sound. Especially since there are thousands of different audio systems in the world today.

If you are looking for certain measurements, you can ask the manufacturer, or have them done yourself. Beware, they are not always cheap and easy to do !