So there are a few parts to this that we can look at. And it mostly has to do with the coming together of US and Japanese tactics and utilization of their respective resources.

But lets consider a few trends and arcs we can examine. First and foremost is that often the USN was purposely choosing when and where to invade, meaning of course they could select where opposition might be weakest, or where they might build a bridgehead before the Japanese could react. They could also land when the wanted.

This last bit is what comes into play at Guadalcanal, because of Admiral King's relentless pushing of the timetable the landings occurred before the IJA/N could secure their new base. Few defenses of any kind or troops beyond engineers were present to contest the landing, and the Marines quickly forced them back towards their secondary positions away from Lunga Point and the airfield. So little opposition on the beach, but across the sound at Tulagi as soon as the garrison found themselves under attack they began a days long fight with the Marines there which would be in many ways worse than the landings on the main island. We can see this pattern of the US and Allies using the size of the Solomon islands to avoid concentrations of opposition when they have to land at all, from Guadalcanal to New Georgia and Cape Gloucester. This would cause a debacle though at New Georgia however when attempts to flank the main Japanese lines bogged down the attack badly.

But a year later when it came time for an offensive away from the Solomons and begin the great advance through the Central Pacific it wouldn't be really possible to sue the size of the small coral atolls to avoid the enemy on the beachhead. Instead at places like Tarawa and Peleliu the Marines and Soldiers were forced to land in the teeth of Japanese defenses. Relying on naval air and gunfire support to cover them until a sufficient gravity of strength was built up on the beach. Then the initial line of resistance could be breached and follow on support landed. Especially on the smaller islands this initial US victory would cause a death spiral of enemy resistance. By showing all their cards, and an inability to defend in depth the Japanese were as fixed in place as their foe, except they didn't have 16in guns and squadrons of CAS backing them up. Once the enemy were not thrown back into the sea it was a foregone conclusion, while the Japanese air forces found their plans to destroy the invasion fleet from mutually supporting airbases to be hopeless as well meaning there was no prospect of relief for the islands attacked. While any hope to stall the US armada was also crushed when the remaining Japanese carrier forces were gutted at the battle of the Philippine Sea when the sortied to counter the US invasion of Saipan.

We also see another increase in the size of the islands being attacked, whereas Tarawa was just .5 square miles, Peleliu was 5, Saipan 45, and Guam 200! That meant the ability for the Japanese garrisons to have room to prepare for defenses in depth if beach defenses and immediate counterattacks were unsuccessful though all were contested at the shore as there are only so many places on any island that are good for landings lots of men and near other important sites like harbors or airfields. Indeed the climax of the landings on Saipan was a fighting retreat by the Japanese until a finale of the largest proper Banzai Charge of the war after the defeat of the Navy.

So with the war coming to its conclusion it was clear that any Japanese island attacked was not going to be saved, but should instead bleed the US as much as they could and tie down their attack. While the advance into more volcanic and mountainous islands also provided additional help to defenders. Coral atolls don't have much natural cover, and the garrisons little spare concrete often.

So in that vein we have Kuribayashi's plan to turn Mount Suribachi into a giant defensive position to command the landing beaches. And to allow enough targets to accumulate on the beach before opening fire as he knew as soon as he did counter battery suppressive fire would start and begin to reduce the effectiveness of his efforts. Okinawa then we see similar, the island is huge by standards of the Pacific with several high volcanic ridges and bluffs to aid defenders and create multiple lines of resistance to drag out the fighting. Meanwhile at sea the invasion fleet would ideally be bled by waves of kamikaze attacks by air as well as they were fixed to the island while the invasion went forward.

While not perfect and still just a modern approximation, The Pacific does a good job of showing as close to "typical" conditions of attacking a central Pacific atoll as you might get, in this case Peleliu which sort of straddled the line between the types of battle as once the defenses on the beach were defeated the highlands and central airfield became focal points for the remaining defenders. https://www.youtube.com/watch?v=LJeA4fpXwM0

Hope this helps! Honestly you just had a bit of luck in looking at two of the battles where resistance on the beaches was lighter for one reason or another.