to be honest i do not like this bar tab idea much. here is why.
you play the man in the middle. you are handling other peoples money.
this means you run a business and need to pay taxes, most likely some kind of licence and also receipts.
then there is also the risk, that the owner will just keep your money, because what do you want to do about it.
i do not see an incentive to go solo. the owner could just stop using bitcoin if you stop the risk free middleman service.
if you want people using bitcoin, then let them use it, do not do it for them.
and there is the problem
people want a store to accept bitcoin but are too scared to stand with the store and help them set it up. they think "someone else should do it" (quoting many other people from the past)
you do realise that although bitpay and coinbase are a 'someone else', but training a retailer about bitcoin, satisfying their questions and aversion to try something new that has negative press isnt going to magic itself away simply because your sitting in your house wishing your local corner store would take bitcoin. if you want your local store to accept bitcoin, you need to be involved with helping them out. not crying from a sofa.
as for needing to be a business. my idea is not a permanent solution and not a solution for national chains. its just a few week introduction which due to not every customer being a bitcoin holder, wont involve much cashflow. and because of this. that small amount of support you offer to introduce them to bitcoin, wont meet the financial thresholds to consider you as a business, nor a MSB in most countries(pretty much all, but i havnt checked them all)
like i said its just a bar tab.
just like prepaying anything.. drinks in a pub, wedding planning, cinema bookings, pre-release video games,
your just prepaying for future customer and accepting bitcoin as a 'ticket' that the business has processed a cash transaction.
if you think a local store is going to do over a few thousand $$ in bitcoin transaction in just a few weeks, then you are mistaken.
in most cases the money you will use as a bar tab is no different then buying a round of drinks for a group of 6 people.
this topic is about local stores.. not international corporations afterall
i see we can agree that you need to act instead of just wining and demanding things happen magically.
but why would you not want to teach them directly. you have to put work into it and explain a lot and set almost everything up for them. work for you in both cases, but i do not see why i should offer a free trial as men in the middle.
i would be even more suspicious if someone would show me a safe way first and then the next time i will have to do it for myself and risk my own money.
this is how a good con works.
so why not tell them from the beginning about the risk THEY will have to take. to be honest works best in these situations if you want long term users. also with own money involved it might need more convincing, but they will put more effort into learning it.
