It's because they are getting so good it's impossible to recognize them.
Haiku 4.5 is already so good it's ok for 80% (95%?) of dev tasks.
I've found Haiku to be truly mediocre for working with. If you want a cheap models, the open source ones are much better
I must be writing very different software than you, I keep opus on a tight leash and it still comes to the strangest conclusions.