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Although Australia has set the threshold for all types of gambling at 18, other countries have their own rules, ranging from state-by-state in the US to uniform 18 + in the UK and differentiated norms in New Zealand.

1. USA: states decide for themselves

Variability 18 and 21
The minimum age for online casinos, sports betting and lotteries is determined by the state: in some - 18 years, in most - 21 years.
Examples

Pennsylvania, New Jersey, Delaware, Michigan, West Virginia - all types of gambling from 21 years old.
Colorado, New Hampshire - online sports betting is allowed from 18, but casino games only from 21.
Gambling laws are regulated by local gambling commissions and can change, so it is critical to check with the rules of a particular state.

2. UK: ubiquitous 18 +

Uniform age for most games
All categories of gambling entertainment - casinos, bets, online lotteries - are available to persons over the age of 18.
Exception for "Category D"
Children's entertainment machines (arcades) can allow players under 18, but this does not apply to gambling.
Tight control of UKGC
The UK Gambling Commission requires KYC verification of 18 + before the first bid and regularly checks operators to ensure minors are not allowed in.

3. New Zealand: 20 for casinos, 18 for lotteries

Casino: 20 years
The Gambling Act prohibits anyone under the age of 20 from entering casino gambling zones.
Lotteries and instant games: 18 years
Participation in lotteries (Instant Kiwi, etc.) is allowed from the age of 18, and other types of unclassified games may not have age restrictions.
DIA control
Department of Internal Affairs monitors the execution - when minors appear in the casino, they face a fine of up to NZD 500 and a ban on returning for up to two years.

4. Australia: 18 + all-rounder

Interactive Gambling Act 2001 fixes the age of 18 for all forms of online and offline gambling.
Uniformity by state
No state or territory lowers the threshold below, be it sports betting, online casinos or bingo.
Control mechanisms
KYC (ACIP), DVS, BetStop and technical barriers ensure that only adults are allowed to play games.

Result

Country	Online Casino & Betting	Lotteries	Note
USA	18 or 21 (by state)	18 or 21	Staff differences; live bets often 21 +
Great Britain.	18	18	Exception for Category D amusements
New Zealand	Casino 20; bets 18 +	18	Casino - 20 years, lotteries - 18 years
Australia	18	18	All types of gambling - 18 years old, single federal norm

Thus, international practice shows that the threshold of 18 years is the most common, however, the United States and New Zealand introduce a higher age for casino games, and the United Kingdom retains a single 18 +. Such diversity is important to consider when benchmarking legislation across jurisdictions.