On a regular Forex platform there are positive and negative interest charged depending on the currency pair and order type. Forex is not as unregulated as you say it; if the brokers activities are regulated, I would say that is some good measures. While using the Forexchief platform I do pay about $2 for a leaving an AUDCHF long position open overnight. So, I am guessing your are talking about swap charges.
Future is regulated market, hence, everything, including costs should be and is transparent. For FX market you need to do some prior research about conditions, as each broker has its own terms, hence, costs may vary
There is interest rate in FX futures but it is included in futures price calculation. I think that this confuses people to think that there is not interest rate element in future contracts. As for FX spot position there is no interest rate included
I don't know if you are aware but long positions on AUDCHF earn sizeable +ve swap with almost all brokers, so your Forexchief broker is cheating
All the brokers I know, withhold some of +ve swap or add to -ve swap making it harder for a trader to make a buck. I use 3 brokers and I monitor their swaps regularly because I keep positions open for days so I will jump on them if I see any very suspicious behavior. Back in December 2018 I saw one of them charging me swap on GBPJPY long positions (when I should have been earning swap) and after I complained they said it was an error so they corrected it.