The payment gateways are subject to the whims of govt. and the payment hosts are subject to the whims of the payment gateways and due to which they're often overzealous and come up arbitrary rules.
I've had YCombinator funded leading Payment Gateways in India asking me to remove links to Hacker News claiming it to be 'redirection' or thinking I'm some kind of "Hacker man" for having the text "Hacker".
I've had trouble enabling subscription payments because I'm a govt. registered self-proprietor and these Payment Gateways decided they will support subscription payments only for Companies.
In fact I've become so versed in hopping between different payment gateways that I'm now building a self-hosted FOSS payment host[1] with support for all major payment gateways so people can have better control over their payments.