That's an artifact of United running SFO-EWR and LAX-EWR nearly hourly. You're not required to take the first available flight, however. Assuming inventory is available, you'll see the same price for any connection less than for hours.

For example, looking at Thursday, 8/24, you can take the 12:30 departure from KOA through LAX, arriving at 9 PM, and then connect to the 10:35, 11:20, or 12:30 AM flight for the same price.

You should see the same basic pattern for all of the flights ex-OGG or ex-KOA. UA will show you the shortest connections first, in most cases, but if you're not willing to chance the misconnect, just look for a longer one.