What’s not factored in the the quality and safety of life in the various countries. $800 a month in the DR won’t get you much unless your willing to live in unsafe areas and exist on a limited diet.I just checked the cost of living between those countries and as of November, 2023 compared to the DR Spain has a cost of living 1.59 times higher, Portugal 1.43 and France 1.88, according to this website: https://livingcost.org/cost
The countries I listed are ones I’ve travelled to frequently. Rentals cheaper or equal to DR rentals are available in much safer areas. Local food market prices are the same as or cheaper than DR prices if your a wise shopper.
Watching how and where you spend your money is the key. Ten years ago, the DR was a cheaper place to live. Not anymore. Colombia according to the site still lives up to its reputation of being cheaper than the DR. Costa Rica is listed as more expensive than the DR but has much a much better public medical system. One trip to a private hospital in the DR can quickly skew your cost of living.
Post Covid, I can fly to Europe cheaper at times than flying to the DR, primarily because of where I’m located. That’s not a factor on the site. Car rentals in the DR have risen almost 50% along with the price of gasoline. The subcompact I rented preCovid was slightly less than $300 for a week. It’s $500 now. That’s not factored in on the site. They do factor in the cost of public transportation.
All the COLA estimate sites factor in different things but it’s a broad brush. What they don’t factor in is the ability of the experienced traveller to cut costs and travel safely. Different strokes for different folks.