Kauai and advance beach/activity booking

I have been planning a trip to Hawaii for a while and am very much a pre-planner and good about booking things in advance. for our trip to Maui, I booked the Haleakala sunrise reservations on the dot with no problems.

Kauai seems nuts though - (at 6:00 AM ET) this morning I was refreshing ahead of time for the Ke'e beach reservations and they just went from not available to snapped up without ever showing as available.

And, I'd been hoping that we could do the irrigation channel tubing trip but they're basically waitlist only for the 6 days in July we're there. (A couple days have slots with 1 person each.) They have 18 trips per day with what looks like at least 20 people per trip and they're all sold out?

Are there hotel concierges ought there booking these all up? Or is there just a massive amount of other type A people out there that I'm competing with? Usually I'm able to book stuff and it's just the non-planners who realize it too late.