If you are on Medicare and traveling outside of the USA, you have no comprehensive medical coverage. There is a clause that you may be entitled to a $50,000 LIFETIME reimbursement under certain conditions. Medicare will not cover any substantial medical problems and most definitely will not cover air ambulance which is inordinately expensive. I have purchased travel insurance several times and most recently from Squaremouth (Tin Leg). We had a trip delay of 8 hours at CDG in France which caused us to miss a scheduled private tour in Casablanca. The trip coverage was for just under $30,000 and the tour company broke out this tour as being $450. Squaremouth requested a variety of receipts including a letter from Experience Morocco which documented the claim but also all of the airline itineraries, airline payment, copy of my credit card bills, etc. After all of that, they found some fine print clause that they applied to my claim despite the fact that I had no control over the delay. If Squaremouth goes to the extent they did for such a small claim, I feel lucky that nothing catastrophic occurred! I will never use this company again.
P.S. Looking through the forum it appears that many travelers have issues with these insurance companies. As an Orthopedic Surgeon for decades, I should not have been surprised and can now add travel along with automobile, homeowners, etc. to the list of how we all experience increasing premium costs while insurance profits skyrocket.