In most US states, restaurants are legally allowed to pay servers a lower "tipped minimum wage" and rely on tips to bring their pay up to a normal wage. This is the single biggest reason tipping is expected rather than optional.
18-20% at a sit-down restaurant is treated as the baseline for acceptable service, not a reward for exceptional service.
Card terminals almost everywhere now show preset percentage buttons, often starting at 18% and going up to 25% or more — these are suggestions from the business, not a legal minimum.
In specific cities
New York City
18-20% is standard, and many servers consider 20% the real floor given the city's cost of living. Some restaurants add an automatic service charge for parties of six or more — check the bill before tipping on top of it.
Las Vegas
Tipping culture runs unusually broad here: valets, bartenders pouring a free drink while you play, buffet staff, and housekeeping are all commonly tipped $1-5 per interaction, separate from the usual 18-20% at a sit-down restaurant. Resort fees already charged at check-in are not a tip and do not replace one.
Los Angeles
Standard 18-20% applies at restaurants. Brunch and weekend rideshare trips are two spots visitors often forget to tip on — both are treated the same as any other meal or ride in LA.
Miami
Large groups frequently find an automatic 18% or higher gratuity already added to the bill, especially in tourist-heavy areas like South Beach. Always check the printed total before adding a further tip on top.
Example: dinner for two in any of these cities
Bill: $120.00 subtotal.
18% = $21.60 · 20% = $24.00. If an automatic gratuity line already appears on the bill, that replaces this calculation — it is not added again.