$80/day? I hope you are exaggerating for effect. If not, they saw you coming.
The minimum SLI (supplemental liability insurance with 20% deductible) is mandatory on all car rentals in CR. It runs from $10-25/day, depending on type of car and agency. You can't waive it, unless your home car insurance will cover you in CR (most will not) and you have a letter or some proof of this. You can waive CDW (collision damage waiver) because most credit cards cover it. I always waive it. There is also another optional insurance that you can take to get rid of the 20% deductible if you have an accident. It costs about $8-15/day extra on top of all the others.
Just so you know... that $230 that you paid for 5 days is a little high, especially if it was a sedan. You could probably get it for $150 for 5 days (April-Oct). So you paid about $80 too much.
I rented an "SUV" (Terios Bego
) in August and I paid $115 all-in for 3 days. The car rate was $13/day and the insurance was $22, plus airport tax. No fighting, no threatening, no attitude, printed out and signed the contract and I was on my way. I think the problem is that you expected the rate you saw on the website to be it, with no other fees. Even in the US, they get you. In August, I had a long layover in FLL so I rented a car from Hertz. I reserved an SUV but when I got there they didn't have one, so they offered me a Chevy Malibu (2 sizes smaller) and graciously offered to not charge me more (for switching cars 
), but the $23 daily rate turned into $48 with all the taxes and fees (incl $9 for 100% coverage insurance-no need to bother with my insurance if something happened). So CR is not the only place that charges crazy fees and taxes.
