I have noticed very few debit or credit cards we have used are restricted for international use. I think most companies dont really want you wasting their time as its delaying them dealing with other customers. Some pay post in on their website but many travel and never bother and never notice.
But i do know when people have either found out that there was an issue with their card being cloned. That or had them blocked when they are or have been abroad is done for totally random events. Like Joe says.
I have had a credit card company ring me up for two uses of my card in quick sucession and then used my credit card in three contients in less than a day and nothing happen.
I do know from experience if say a company delays processing a payment form your debit card (some uk based shops in the past have not gone though for a couple of weeks in my experience) this may with some software if you then use it in phill or wherever abroad confuse them as the same card is used 8000 miles apart at the same time.
I know of people who have had this happen, a quick phone call sorts it out. But thats not always easy when in the middle of no where and unsure why its blocked or not working.
Credit card use in phill is rapidly changing i remeber only mastercard being accepted in many places in 04 by 05 visa was everywhere. But most from memory dont use chip and pin which is a good on the point of the bank covering any losses but not so good as its so easy to have someone misuse it.