The most obvious example of this is websites from the UK or Europe which operate any kind of gambling. [1] This may well be legal (based on licensing) in their jurisdiction, but they still need to restrict access to prevent US people from accessing the service or they will be breaching the US's gambling laws.
Likewise many US firm geofence access for EU residents out of fear of GDPR.
People hosting news sites have often had to geofence to prevent UK residents from accessing their site if they are hosting any kind of reporting of UK court cases that are under embargo or matters that are subject to one of the UK's famous "Super injunctions" [2]
[1] eg this guy was on the board of a listed UK company operating as far as they were concerned entirely legally who was arrested in NYC https://www.theguardian.com/business/2006/sep/14/gambling.mo...
[2] eg In the "Ryan Giggs" super injunction case https://en.wikipedia.org/wiki/2011_British_privacy_injunctio...