A slight oversight?

Oil Products are important, like REALLY important. So important that some industrial and most modern era units REQUIRE them.

However there are only 3 ways to acquire Oil Products, one of which is an UB for Japan and the other a National Wonder you unlock near the end of the modern era.

The last and "main" way for one to acquire it is through use of an oil refinery. And here's where the problem lies, it requires river access. This leads to an interesting situation on maps completely devoid of rivers, where wars are fought solely by Infantry and Howitzers since they are the only thing you can actually upgrade since units like Cavalry gets demolished since without Oil Products they stop at Light Cavalry/Cavalry and Tanks can't even exist in the first place.

"The year is 1990, we have just constructed The Internet. Airships are non-existent since SAMs are rather effective against them for obvious reasons. On the Naval side, the world experienced a period of time where Subs dominated the sea due to a lack of Destroyers that could see them. Land battles are massive clashes of infantry and howitzers slowly marching towards one another unopposed by anything else. One of the few forms of travel between cities is through the advanced electric railway system or by airship."

It's a bit silly.

I think in this case the problem lies in a map without rivers. Totestra mapscript sometimes generates such maps, but that's the real bug.

OR You could look at it as a new version of reality.

A "what if" mod, oil was never available, what would the world be like.

But looking at it from our reality, its a MAJOR BUG, but no rivers, I play continents exclusively and never have struck that problem.

Bug with the map script, or deliberate setting in script.??

By the way, why does oil refinery need river access?
The bottling factories surely need it so it would make sense to add this as a prerequisite for brewery.