>or perhaps scarcity existed in terms of time it took to procure materials.

I would say this is pretty much the case.

Even the simplest most abundant resources takes time to harvest. And that rare resources take much longer to fine, and can be much more dangerous to gather (requiring people to suit up with a set of expensive gear that they could lose in the process).

What makes different servers so diverse is that mods can drastically change the underlying cost and risks of gathering material. There is a turtle mod that allows you to program a turtle to mine resources for you. While it is kinda slow, it runs steadily without intervention and can quickly strip mine an area to provide you with plenty of resources. But it can't farm animal items like wool, so it significantly lowers the time investment of ores while not at all impacting animal product costs.