I'm wondering how much you would be willing to pay, either as a percentage or a flat fee, to have every invoice you send out to clients paid within 24 hours?
As a managed IT service provider - absolutely nothing. The current fastest method, credit cards, we don't generally accept. The rates we pay to accept credit cards or PayPal are already so high - I don't normally accept those types of payments unless the customer is willing to pay a service fee.
In Canada, we have Interac, which is also instant. But not many of my customers want to use that either because, you guessed it, service fees. Even then, these payment methods make their lives easier, not mine. I've built my business around 15 days min to receive payments. 99% of them are fine with cheques. So there isn't much incentive for me to consider this.