Yes and no. The UK has a lot of earning potential, but a lot of it is vulnerable to attack or capture, making UK very “swingy”. If things are go well for the allies, UK will be pretty wealthy, if it goes badly UK can end up being very cash strapped indeed. Playing with national objectives (which is the way I prefer to play) will amplify this even further as the UK is the easiest ally for the Axis to prevent earning any bonuses.

Meanwhile the US has a huge does of IPCs that are rarely touched by the axis, even when things go badly for the allies, and is also the only nation with 20 ipcs of objective bonuses available, so the US is still very much the big spender of the game.

As to what’s in it for the US in the pacific: Its less about increasing US earnings and more about limiting Japan’s. Left unchallenged Japan can reach stratospheric income, bringing the UK economy to its knees as they drive to Moscow.

There are also two pacific based objectives for the US, so that adds 10 potential ipcs of direct incentive, plus the chance to pick up one more for the UK and prevent Japan from earning any, which stacks up to enough money to justify a US fleet investment.

I find allied players that are good with a slow push play style do well fighting it out in the pacific, but those that are better at a quick kill/knockout blow style will have more success trying to kill Germany before Japan gets too big. I also find a pacific allied strat is more likely to work in the 1942 set up than it does in 1941. (Part of the reason I like that set up better)

Without objectives it may be better for the allies to just fight a delaying action in the pacific and focus on Germany, but I have not played that way enough to say for sure.