Splain it to me Lucy, please

I am a very new newbie to Kodi. I have a real nice android box that runs Kodi 16.1 very well. I have added a number of sources and that seems to work BUT

I would like to PVR some shows but it looks like each service/addon has its own PVR. I am confused. How come one size does not fit all? Why is there not one simple PVR function that works for all services? Can someone please help me understand this? What happened to the concept that the PVR was related to Kodi, not the addon?

Getting back to simple PVR… I have a Diamond TVW750U USB ATSC TV module. Is there a simple Kodi addon that would let me use this to watch / record OTA TV? I looked at this and scratched my head, but found no answers. Hopefully, someone who knows what the hell they are doing can point me in the right direction to get this figured out. At least, I sure hope so cause I am lost on this one.

I sure hope someone can point me in the right direction. Is there any kind of simple manual that I could read to get started?

I am trainable.