Because the US still does not have instant, or near instant bank transfers. ACH bank transfers cost money per transaction, on the order of 0.30-0.50 per transaction, and can much higher for larger transactions.
The US is just incredibly, and uniquely behind when it becomes to accessible payments. This is the reason why "FinTech" such as Cash app, PayPal, and Venmo, in addition to credit cards, are popular - they literally just don't have the infrastructure in place for you to pay back a friend after they pay for a meal.
Every other developed, and even some developing countries, have had fee free instant payments, for the better half of a decade. The UK/Hong Kong have Faster Payment System (FPS). Europe has SEPA, and most countries mandate that transfers cannot charge fees. Australia has Osko. India has Immediate Payments Service.
I read horror stories of USians paying rent by writing cheques or mailing cash to avoid bank transfer fees and subsequently stressing out about fraud. This is just insane to everyone else, who just pays via instant bank transfers.
That's even more confusing, why not forego the shower glass entirely and just have a shower curtain instead?
Yes I know it's likely retrofitted, but I won't pass a chance to say that shower curtains are superior. Shower glass looks glossy in brochures, but everyone IRL has a sad squeegee hanging from it.