That’s because the volume of sales is too low.
And it’s low, because 1. people can’t place very long term 2. people are limited in offers number 3. 0.01 isk warriors are a thing. While in RL 1. you place several years-long orders 2. You place as much as you want 3. your orders are delayed OR bots are allowed (like, they are built for bots)
CCP mixed the long-term and short-term markets (regulated and OTC), making each suffer from the issues of the other.
edit : I’m not saying it’s good or bad. It was their choice, they have constraints and it still works somehow.