I had this happen the last time I ever ordered a pizza delivery (I also became so irked at the price that I’ve made my own pizzas ever since.)
Here in the UK there’s no obligation or expectation to tip, so that never even crossed my mind. And the pizzas are already so egregiously overpriced that I’d be put off tipping anyway.
I hand the pizza deliverer a £20 note… and then hilarity ensues as he’s about £2 short of the right change. He offers me a voucher I can use on the next purchase. I refuse the voucher and explain to him that I prefer money, as money can be spent anywhere on whatever I need, and that I don’t know when or if I’ll ever buy a pizza from them (Pizza Hut) again. The delivery guy now looks rather sheepish and bemused and he again tries to offer the vouchers. I again explain why I don’t want vouchers.
I eventually looked to see if I had the exact change myself, and came back with a handful of coins that took another minute to count out… and I was something like 20 pence short. He hesitated, and then accepted my payment as if he was doing me some huge favour.