As SLF involved in the supply of items for on-board sale and retailing in the airport the naivety of some people amazes me. Lo-cost is exactly that for a reason in the same way as Full-Service needs no explanation - the lines blur in some middle ground cases but generally people should know what to expect. If I travel on Lo-Co I eat/drink beforehand and carry on a bottle of water (from the airport at a slightly less exhorbitant price than on-board) but I do this in the knowledge that generally the overall cost of the flight, food etc is less than the full-service price.
What may be more interesting for you to know is that your company sees selling water, tea, coffee, snacks etc as a profit generator - pax A has spent £5 + tax on a ticket but then spends another £5 on a coffee & sandwich of which £4 is profit. Your company generally will buy the product at a lower price than Tesco etc, will earn a substantial sum for 'advertising' the brand and still sell it at 3-4 times the retail price.
On this basis I can understand some airlines getting slightly miffed if staff were to hand out 'free' water. In an isolated instance this can be overlooked but start doing it for everyone and someone will soon cotton on and stop providing any form of cup on board. Let's be clear that society has moved on over the past years and everything has a cost to it which needs to be covered by someone and I'm sure crew wouldn't expect it to be from their wages.
I'll crawl back under my rock again and watch from a safe distance.