I came across
https://buy.bitcoin.com/ and I was wondering two things. Are they trustworthy? and also, can somebody from New Zealand or Australia buy BTC or BCH from them using their credit card?
They are most likely going to deliver the bitcoin to you if you used them.
Doesn't mean you should use them, though. Firstly, they are using using the bitcoin.com domain as leverage to promote their shady BCH movement which I don't support. You can even see this as on the buy.bitcoin.com bitcoin cash is listed as "recommended".
Secondly, their fees are extremely high. $10 minimum on Simplex's part, and 5% otherwise plus bitcoin.com's commission of 2.5% leaves a rate similar to virwox's.
My suggestion would be to use them as an absolute last resort, if you can't find anywhere else to buy at then they're not going to scam you, make sure you choose bitcoin core instead of bitcoin cash when you actually buy anything. But their entire site and agenda is shady and I wouldn't use them personally. There are plenty of alternatives, with way better rates especially for smaller purchases (since there is a $10+ minimum fee on their site).