Why does it take so long to transfer funds from one bank account to another?

Typically ?not here. free inter-bank transactions overnight here.

Here in Australia I can be confident its max 24 hours if the start and finish are business hours monday to friday, and its started in the morning… They do the bank to bank transaction instruction passing around lunch time and afternoon and then update the customers accounts overnight… so if I do the transfer at 9am monday, then its the recipient can see it confirmed in their bank account , eg able to withdraw it as cash, sometime after the early hours of tuesday morning…maybe delayed sometimes, but by lunch tuesday at the latest.
So I guess that confirms that the banks can reasonably do the transfer overnight at the slowest, but if they are all in a cartel that agrees to charge $30 for it, that does sound like a good reason why… here in Australia the bank fees had to reflect actual cost, on average. There’s been class actions (plaintiff being the banks customers) recovering fees the bank charged above actual costs. Some of the banks were imposing a cost recover scheme where they would give 10 free transactions, but thereafter the fee per transaction quickly recovered the costs of 50 transactions…meaning that on average there were no free transactions… ah no there has to be free transactions … the average transaction charge has to reflect the cost … not the ability to be profitable… There’s all sorts of fees and penalties that got into this class action, but thats the general gyst of it.

I bank at a Savings & Loan. I’m not enough of a financial expert to say what the difference between this and a “real bank” is except that I used to deposit with a big bank and hated the way I was treated. (This is the US.)

My S&L clears deposits instantly, with very few exceptions. I’m not sure what would happen if the checks ever bounced, but there have been occasions when I’ve deposited say 20K and I could have walked out with that amount in cash if I’d wanted to. I could go on but TL;DR look for a local savings and loan.

Banks send and receive transactions via the ACH network once a day. Mine does it at 3pm. Not sure if that is a universal time, or just the one we chose. So if you send funds via ACH before your bank’s cutoff on Monday, they will leave your bank at 3pm Monday. They will arrive at the other bank at their cutoff on Tuesday (probably around 3-5 pm). That bank may post the deposit by Wednesday morning if they are large and sufficiently well-staffed, but may take longer depending on staffing rules, their internal policy, and whether the transaction appears to be suspicious/is over a certain amount. Our Cash Mgmt dept works until 6pm in my bank, so there’s a chance that such a deposit (even absent any suspicious factors) may not be posted until Thursday morning.

If you want your funds to move faster, you need to wire them. Wires travel via the SWIFT network and will post to the other bank same-day if submitted prior to the bank’s cutoff time (for us, again, this is 3pm). ACH is slower because it’s cheaper. At my bank, it costs $35 to send a wire-of any amount-and $15 to receive a wire.

This is fraud prevention, and has nothing to do with the ACH network

Just to give a Canadian data point - if I transfer funds between my TD Canada Trust and my Tangerine (formerly called ING Direct) bank accounts the transfer shows up in the destination bank account late in the afternoon (4ish) of the next business day, assuming I request the transfer early enough in the day (I haven’t bothered to experiment to find the cutoff time). Interestingly, if I transfer money to Tangerine it gets frozen for 5 business days (I can see it in my Tangerine account and it collects interest, but I can’t do anything with it); however I have never had TD freeze my money when I transfer to TD (there may be a limit, but it is above several hundred dollars).

Many fraudulent cashiers (and other) checks out there.

I often suspect that some institutions hold the money for the maximum amount of time, regardless of the actual time.
But immediately add it to one of their own accounts that can earn them some money in the meantime. On a large scale, this might make them some sizeable free money.

But as someone mentioned. The electronic transfer system is surprisingly archaic and muddled. Also skimming off charges along the way.

Correct!