We're switching ACH to Dwolla since it's far cheaper. The 1.25% for the new ACH 2.0 for faster payouts (which we require) is outrageously priced. It basically cut our revenue in half overnight once we got out of the beta for it.
You don't have to run kubernetes for containers, but even then, only 4 of our engineers know and operate kubernetes. It allows us to enforce routing, authn, and authz standards everywhere (and test locally). Application engineers only need a simple command to run their stack and some code templates to build and test applications. Not much knowledge is typically needed on their part. Is it always perfect? No, but it's a lot simpler then wiring up a bunch of vendor specific offerings.
It's alright, but continued to find bugs and edges cases with it. The challenge is when there are a bunch of integrations cross-accounts, eventbridge, cloudwatch, etc. that you just can't emulate well locally. Or once you do, it doesn't work a month from now because things change (e.g. a developer is using a new feature that isn't supported by localstack or something). In container land, you don't have to worry about these cloud integrations. You just spin up the services you want in a docker compose file, k8s deployments, helm charts, etc. and you basically have everything without having to worry about being a AWS specific blackbelt guru expert.
My previous company had thousands of lambda functions and api gateway integrations and near impossible to do anything with confidence when you starting integrating with all the other cloud offerings. My current environment is similar scale, but all containers it's night and day difference when it comes to confidence. We can move 100x faster when you can reproduce environments locally or separate account in seconds or minutes with everything baked in. I don't think I could move back, but hey at least this might eliminate a few API Gateway integrations.