Because the market is not very large and there are many legislative and bureaucratic impediments to them. Taking payments online are one, just because there is no legal framework for them in most countries. Reliable internet and broadband connectivity. And mostly, a culture of risk adversity that is rife in the Caribbean.
That’s not to say that some have not tried to do something. There are a few, but the impediments to them creates a huge barrier for others to follow.