Those are local APIs in the OS on the TV available to apps that run inside the TV. Regardless, it likely even if running on the TV it would not provide power control when the TV is turned off because the CPU is turned off.
A simple test to prove the inability of Samsung TVs to power on via IP is to use nmap while it is turned off:
nmap -v -p1-65535 -sS 192.168.1.151
Replace the IP with your TV’s IP and you’ll see the port is completely dead on all ports when it is not on. It also does not respond to network layer packets like WoL.
We’re about to deploy a large update to Samsung’s EX-Link Serial codes with 3D, explicit Brightness/Picture/Contrast commands, etc. It is safe to say that serial is the best way to control Samsung TVs if your model supports it. Surprisingly, most models do have it this year, but some of the 9000 (top end) models do not! So make sure to confirm the model supports EX-Link before buying if you are not planning to use infrared control.