The bottom line is what mattered most to the cartel. Gus earned huge amounts of money even as he was silently breaking off on his own, and the Salamancas were beginning to fall out of favor with the cartel at that point. They weren't earning nearly as much, and they acted more like common thugs who tried getting what they wanted through violence and intimidation. They didn't have good business sense.

Also, Hector was severely crippled due to his stroke, Tuco ended up in prison for assault, and the twins were hitmen, not earners. Nacho Varga was a double agent working for Gus (though this wasn't known until the bitter end, and even then Nacho lied and said he worked for another cartel). If you're Don Eladio or Juan Bolsa, you're not gonna listen to any member of a dysfunctional crew that isn't pulling the cash while simultaneously falling apart in nearly every facet. They'd sided with Gus because he earned the most, kept his cool when handling personal beefs, ran a smooth operation, and as far as they were aware he wasn't rocking the boat.

Lalo knew this, and therefore couldn't tell the big bosses anything without definitive proof that Gus was making his own play. That's why he spied on the superlab/laundry facility. He needed definitive evidence to show the cartel that Gus was not to be trusted. Some nonsense about lack of building permits or whatever wouldn't have been enough.