It's still definitely possible to earn well from showing as a premium member; you just have to be more specific with which horses you enter. Premium members only compete against other premium members, as far as I'm aware. As they're generally the more experienced/serious users and can use the barn manager, the showing is far more competitive. It isn't any biased coding that makes it this way - it's just how the game works.

As a free player, I entered any horses who got over 70% or under 20 faults. However, as a premium member, I've found I just have to be much more strict in order to make the same earnings.

In looking at your horses, you're showing a lot of low level horses. These automatically will mean that you won't earn a lot of money off of them. You're also showing a lot of horses with poor training/aren't trained enough. These horses will lose money.

I'd suggest taking a look at one of the showing guides and then looking over your geldings. For the ones with heavy weaknesses, I'd try to find a SD that they're strong in and train them in that.

Pandemonium said:

I generally do between 5k-20k (once had almost 30k for my less than 200 competitive showing horses) profit each night of showing. My BM is set to only competitive and only SD horses. It is quite possible to make money from showing. I have some weeks where I'm only just breaking even cause a lot of my horses level up in the same week or two and require a couple weeks of training before they're able to make money again.

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My real money makers are my SD world class geldings. Wayyy less training required thus more often in the money!