I’m not sure what you mean by credit card usage but if you look at the statistic on the central bank’s website. Credit card transactions and debit card transactions values are almost the same.
Annual Credit card stats
Annual Debit card stats
The number of people that have credit cards however in Trinidad and Tobago is indeed low only about 20% of the population about 15% in 2015 if you do the math. However what you really want to look at when creating a business is how much people spend.
For online business alone “Finance Minister, the value of packages cleared by local courier companies was about $1B TT Dollars per year.”
Which says to me that the 20% of the population with credit cards are spending their money. If anyone can build a online business locally that could keep at least 10% of that money in the county. I think it will benefit all of us. Rather that try to get debit card holders to make online purchases or build entire business on the promise of buy in for debit card holders.