What's with $40 for 1 camera $150 unlimited and nothing in between

Hi, I'm new to this so apologies if this is a well asked question. I have one ring camera and pay $40 Aud for my ring pro protect plan, I want to buy a second camera, however the next plan upgrade for more than one camera is $150 which to me seems like a crazy pricing strategy. To me it seems like by paying $150, I am getting ripped off if I don't have 4 camera? Can I pay $40 twice or does the plan not work like that? It's not really the cost, more the principle and getting poor value for money. Thanks in advance.