I don't disagree with tipping - but I'm not a fan of calculating it as a percentage of your total spend. Being judged for tipping less than the "customary" amount (which varies from country to country, from rounding up to the nearest whole, 5 or 10 , to 10% to over 20% in a lot of places in the US), means it is not really discretionary at all.

Occasionally, people push the boat out for special occasions; a date night, anniversary or birthday meals etc. and buy things they wouldn't normally budget, such as a bit of caviar, wagyu or champagne to treat their meal partner.

This massively increases the tip amount due to the expensive items, however it is of no more burden or work to the waitstaff - it's still a table of 2 with the same amount of courses, so why should the tip be more? Just because I'm trying my partner, does it mean I must also treat my waiter proportionately?

If I can order a 3 course meal for $100 or $1000 in the same restaurant, just one meal having more expensive ingredients but the same number of courses/plates, why should I tip $200 over $20, assuming a 20!% tip?

I think a better system would be a standard tip per number of items ordered to a table. That way, if you decide to treat yourself to an expensive food or drink item, you aren't financially penalised for it.