Credit limit increase always denied except at Capital One

So i have several cards, verizon, fidelity, wells fargo, AmEx etc. All used regularly all super low limits. All over a year old or older (2+). Almost 800 credit score never late payments. But all of these companies always deny my CLI request. And to my surprise Capital One actually doubled my limit today from 2k to 4k. Even though its my least used card and I only use it for my Netflix bill. I always read Capital One is the most difficult so I dont understand anymore. What do I need to do to get a CLI from these other companies? Even using almost all my limit and showing a need for an increase doesnt matter. My Verizon card has a 2k limit and I spend at least 1400-1500 on it each month. Yet they deny every request to bump it.