Coin production is ridiculously easy, and if there's a lot of coins spending in SAM, then good. There's not much to use it on anyway.
Before I leveled to ME, I was doing the Fnord recurring quests 5 times a day. In PE, that's collect 280k coins per quest, and 5 times is 1.4 million coins. There'd still be a good amount of coin left over afterward, but not enough for a 6th, but I estimate a daily coin production of around 1.5 million. I haven't relied on goods production buildings since EMA, and unit recruitment when I took losses were pretty cheap, a tiny fraction of what I was producing. So that leaves what, Unbirthday RQs? So they piled up. When some of these new event buildings are producing 80, 90, 100k coins every 24 hours at PE, there's a lot of money coming into the city.