The manufacturer of your laptop has paid Microsoft for the OS and is passing that cost on to you in the total price (excluding MS hardware such as the Surface).
Or if you buy a bare system or build your own, you need to buy Windows yourself.
Apple gives their OS away, but in theory you can only run it on their hardware.
When you buy a Mac you are subsidizing the development of that free OS. The the price of the OS is baked into the MSRP in both cases. Comparing the prices is apples-to-apples. Also, Microsoft has made it clear that Windows 10 will be around for a long time, so OS upgrades don't work the same way Windows once did.
Or if you buy a bare system or build your own, you need to buy Windows yourself.
Apple gives their OS away, but in theory you can only run it on their hardware.