Look at it from the bank's perspective:
Somewhere in Europe, presumably, you've got a primary residence. The bank knows 1) the property, 2) the market, 3) the stability of the local/provincial/national/regional government and economy, and 4) can reasonably predict valuation trends.
In DR, however, they know that most who buy property see it as expendable. There have been a few posters that talk of shuttering - not selling - their houses in their native countries. The bank knows that you'll do virtually anything to keep from losing your primary residence, including walking away from a vacation house. You may plan to live there, but the bank still sees it the same way. The best way to keep you honest - and paying the mortgage - is for you to dump a significant amount of your own money into the project.
Also, they also know that far more houses are bought than sold in vacation areas, and that people don't buy property, they buy sun, sand, shore, and the escapism fantasy. They're simply throwing in the house for free. Which means that people tend to stop being reasonable and start overpaying. Most banks typically require you to put down 5-20 percent of a property's true value for primary residences. Higher LTV's are typically reserved for investment/vacation properties, or properties which have been overpriced. Therefore, if a bank is only willing to put down half for a house, that should tell you something.
DRob:glasses: