You are probably 100% correct. The airport departure fee/tax is now $42 (way back when it was $5) and also the SXM airport Improvement fee of $12.50 pus two different security fees of $13.73 total over $68 to leave the island, why not add on another $15 to arrive on the island?
Ignore the total price as I just put in some random dates on Delta to see what the taxes/fees were on a ticket to SXM