Late Developer:
I agree! The 200mm lens was an attempt at humour - that would look dodgy and and would likely get folk worked up very quickly. I have in mind the tourists to the Sunday market, rather than local businesses & their employees.
I was onced asked by a London council to do a calendar for their tenants. When they rejected my initial 'concept' of a local nude lady for each month, we settled on local buildings and well known scenes. There was this fantastic mini-market with stalls on the pavement with every kind of exotic fruit and veg on display. The sun was on the scene and locals were walking past in their ethnic dress. The shot didn't have a lampost or a street sign in it - this was straight out of Asia, rather than London. Setting up the tripod to take the shot, the manager came out and told me that I needed to ask the (absent) owner's 'permission' to take the shot. I explained that this was for the local calendar with a print run of tens of thousands, all delivered to local addresses. Unpersuaded by the offer of free advertising for a month in the homes of locals, I packed up and wandered on to take a photo of a lake. Out of a sailing clubhouse (about 100m distant) bursts this officious fool that tells me that I am 'not allowed' to take a snap in the park overlooking the empty lake because 'children learn to sail here'. 'But there are no boats out there today' I countered. 'Doesnt matter he said - there might be'.
Given the fact that the job was for the council, I resisted telling him that I was perfectly entitled to snap what the devil I wanted and slap him across the back of the head with my Manfrotto tripod, with extra ballast being supplied by a Leica R8.
So yes, I am very used to people not wanting to be snapped, which is why I have decided to ask for this Instax moment.
But what I really don't get, is the ignorance of the public. If I wanted to surrupticouly snap a brat in a boat or a supermarket which may or may not bank all its cash, would I really mess around with a tripod, big camera, light meter etc? Or would I be more likely to use, say, a mobile phone? Or I hear that one can now get film-free cameras, where one just point and clicks while looking vacuous and disinterested.