Is this also a requirement under the B2 Visa?
The answer is no, but I can understand the confusion. CBP never normally ask for sight of return tickets (these prove very little) but it is not really CBP you need worry about as compliance with immigration documentation is largely left to the airlines - under threat of a fine if they make a mistake in allowing you to board. It is your carrier you need to convince you have the paperwork required.
Airlines rely on TIMATIC and an extract of that kindly provided by KLM is:
National New Zealand (NZ) /Embarkation New Zealand (NZ)
Destination USA (US)
- Passports issued to nationals of New Zealand must be valid
for the period of intended stay.
Visa required, except for Nationals of New Zealand with a
biometric passport and an Electronic System for Travel
Authorization (ESTA). They must travel as a tourist, on
business or in transit, for a maximum stay of 90 days. (SEE
NOTE 60190: Passengers must hold a return/onward ticket.
Visa required, except for Passengers with an Authorization for
Parole of an Alien into the United States (Form I-512).
- Children, up to/incl. 15 years of age, being nationals of
New Zealand, are not allowed to enter the USA on their
- Minors traveling unaccompanied, or accompanied by one parent
or a person other than parent/legal guardian,
For details, click here.
- The following applies to those traveling under the US Visa
- Passengers must have a biometric passport.
Passenger must obtain an ESTA authorization via
Detailed information on the new ESTA restrictions can be
A return/onward ticket (or electronic ticket record) must
be to a final destination country other than Canada, Mexico
or contiguous (adjacent) countries or territories situated
in or bordering the Caribbean Sea For details, click here . If a
passenger holds proof of residence in Canada, Mexico or a
contiguous (adjacent) country or territory and is
transiting the USA to that country or territory, then an
onward/return ticket to that country or territory is
Passenger can make side trips to Canada, Mexico or
Caribbean countries/islands, provided first entering the
USA on a carrier participating in the VWP. No additional
time is given (extension) based on the departure to
contiguous (adjacent) territory For details, click here .
- A passenger may enter the USA with a valid visa in an
expired passport, provided For details, click here
- Visitors are required to hold proof of sufficient funds to
cover their stay and documents required for their next
If you filter out all that does not apply to you I think all that is left is really that last bullet point and documents required for their next
destination does not include a ticket to get to that destination.
In case it helps, for a B-2 visa to be issued there has been some vetting of suitability, to a degree greater than for an ESTA. So it is not surprising that VWP requirements about onward travel are stricter, though in other respects (eg activities allowed once in USA) VWP and a combined B-1/B-2 are equivalent.
Given that your travel agent is unsure (and the layout of the TIMATIC data!) it might be as well to check with your airline, either in advance or at least allow extra time for check-in so any misunderstandings can be corrected. Since New Zealanders mostly qualify for visa waiver, I suspect there may not be much familiarity with B-2 visa regulations and it would be easy to expect that a return ticket is required for B-2 holders as well as those travelling under the VWP.