If not, what's the difference between a publicly funded healthcare system and a publicly funded food stamp system?
Anyone in canada is able to take advantage of the publicly funded doctor. The system is purposely setup to cover every canadian. Only low income Americans are eligible to take advantage of SNAP and Medicaid. The system was originally designed to help people for relatively short periods of time when they are between work that pays them enough to not need the assistance. In fact, part of the reason many people dislike these programs are due to the mythical "welfare queen" that stays on programs like these for years and chooses not to get a better job because that would mean no longer getting the free (to her) assistance.
If every American was eligible to be on food stamps for their entire life, then there wouldn't be a difference. But that's not how food stamps are designed nor how they work.
It's actually a little surprising that the concept is not given more attention, at least in countries with socialised health care. It would be a very hard sell in the US.
Part of the problem with giving a basic income is how much to give people due to variances in the cost of living. Someone in east san jose or oakland will need much more money than someone in East Nowhere, Midwest to acquire the same things.
I'm not saying that can't be solved and then done, but it will be complicated and as you mentioned a very hard sell.
EDIT:
Food stamps could totally be designed to be a long term program that every american is eligible for. One way would be through a tax deduction/refund. It would need to be more than a refund, though, to cover instances where people don't have enough taxes to use the entire deduction. Also, it assumes people would be smart enough to use it for food and not big screen tv's.
I think extending the current program to everyone would do a better job of ensuring everyone has access to food than just giving money. The current program basically gives you a credit card every month that can only be spent on certain food items (eg no alcohol). Sending those to every family once a month (or allowing it to be picked up from a dmv-esque office for people without an address), would ensure that people have access to food (there are already measures in place to prevent someone from selling their foodstamp card for money). heck, if you wanted to get fancy, you could even allow/extend the card to be spent at restaurants.
Social Security, SSDI, Welfare, WIC, EITC, SNAP, section 8, etc
The fact it would result in higher SS payments to old folks would likely make it widely popular as well, as well as the removal of Minimum Wage.
I have no illusions about this: additional revenue will be required. Also many federal employees will be let go if you do this. They handle minutia around all these programs that could be replaced.
>Basic Income would probably decrease SS payments to existing retirees
Some existing retirees, the >3k a month ones perhaps. Many people are retiring far earlier, and in the 1800ish area. Those will likely see increases (remember, this has to replace section 8 as well).
Food on the other hand, costs a non-variable amount and is relatively inexpensive.
The two examples you give are not at all similar.