ACH in the US is not simple to use. Companies that accept ACH payments are using a payment processor that comes with a fee (usually less than credit card fees); contractors aren't going to set that up. Consumer to consumer transfers built on ACH have increased in the last couple of years, but with low limits, inappropriate for contractors, and generally with terms of service prohibitting business use. It's easy to move money between my accounts with tools based on ACH, though. There's nowhere at my bank where I can say send $x to a routing number and account number, it takes a bunch of setup work.

Wire transfers are expensive here; my credit union which doesn't generally have high fees, charges $29 to send a wire (they don't charge for incomming wires, but some banks do). I've had some brokerages with free wires, but usually that's tied to a balance requirement or in connection with a company sponsored account (for stock based compensation or retirement accounts).

In the US, wire transfers can incur fees for both sender and recipient. ACH is more often used by medium to large businesses transferring money from or to consumers, but the ergonomics are pretty bad for one-off person to person transfers, to the point that if you hire a plumber who owns their own business, they'll probably accept check, and sometimes accept credit cards.

The US does have some electronic networks for instant, no-cost p2p payments. https://www.zellepay.com/ has a large number of participating major banks with some major exceptions. A lot of people use https://venmo.com/ or https://cash.app/ which are not directly integrated with banks but then offer electronic transfer of funds to bank accounts.

Australia too. Electronic transfers here are free and instant. When I used to rent I just set up a recurring payment through my bank’s website (free and easy, with any bank to any bank). Now my mortgage gets taken out each month automatically via a direct deposit authorisation. (ACH equivalent).

Wire transfers from my bank in the US require me to call up and make a request.

Writing a check is the fastest way for me to transfer between two accounts. :(