Aye.

I think this may be a matter of efficiency. NOTE: I am approaching this with somewhat limited experience, only having patronized restaurants in the US, and seldom gone higher than the average chain restaurant, so my perspective may not be the same as yours, but...

The fewer types of glassware a restaurant has to maintain, the easier it is for them to get bulk discounts on replacements, the easier it is to efficiently store and wash them, and the easier it is for the waitstaff to access them and get them to the filling stations and out to the customers. Ease of use speeds service.

Sure, alcoholic beverages still come in a variety of different containers, but those are handled by the barstaff, not the waitstaff. The waitstaff can simply pull 6 generic glasses out of the hopper and fill them with whatever - water, pop, tea - and they're done, saving them the time it may take to hunt for specific glassware and move around to multiple locations to fill it. It's a model that's been used at cheap restaurants for decades, and I think the sense it makes may be permeating the upper end restaurants.

I realize that some people will have preferences different than mine, but aside from personal preference, I really don't see any compelling reason for a restaurant to maintain separate sets of glassware for water, tea, pop, and any other non-alcoholic beverages, when a single set will do. What size, shape, and material they choose is up the individual restaurant, but there are definite benefits to larger sizes and plastic materials - larger sizes mean less frequent refills, which frees up a lot of the waitstaff's time, and plastic means fewer broken pieces in the washers and on the service floor. Plastic also means safer, because no one on the restaurant's staff will have to pick up potentially dangerous sharp pieces, and no customers will be exposed to potentially dangerous sharp pieces. A mop is all that's needed to clean up a spilled drink.

Plastic containers can also improve storage and staging; glassware often doesn't nest when stacked, meaning that water glasses have to be stacked the old-fashioned way, with trays between each layer. The stacks get high, heavy, hard to reach for shorter staff, and darn dangerous, not to mention difficult to move around from the washing station to the dispensing station(s). Plasticware nests, and is 1/4 the weight of glassware, so it's much easier to stack it safely next to the dispensing stations in easy-to-reach places.

All of this efficiency reduces the amount of time it takes for the waitstaff to get things done, which means that a) the same waitstaff can handle more customers, or b) the same number of customers needs less waitstaff - which translates to monetary savings and thus greater profits for the restaurant. Which they may or may not choose to pass on to the customers in the form of lower prices.

Right or wrong, agree or disagree, prefer or not, I believe that's what's behind the trend you're noticing with water glasses. It seems a small thing, but it's part of a larger picture, and that picture is constantly evolving.

Perhaps in some places that is the reasoning, but most places I go to, drinks (including water and pop) and dispensed in the bar area, where all the glasses are available to them.

In terms of the glass v plastic, plastic is definitely lighter and stackable, so space saving is one consideration, but having bar tended and managed a restaurant, the space really wasn't a huge factor (and our bar was very busy, hundreds of people at once) we stacked single stack, on wooden shelves, all below waist height (no balancing or safety issues). Plastic is often less hard wearing than glass (scuffs up quicker in dishwashers, cracks when dropped on hard floor etc) but breakage was never a huge factor for us either (I would guess we had more stolen branded glasses in the bar than broken TBH!)

I've never been served water in a plastic cup while my drink is in a glass. I often order a glass of ice water in a tall glass and that's what I get.

Reusable plastic cups are often given free by Coke/Pepsi for advertising. They will also not break as often, so will end up costing less in the long run. They won't break in the ice causing an ice bin melt. It may also help to indicate that the 17 year old at table 20 is drinking a Coke and not a Rum and Coke.

Most of my bartenders know I prefer glass and will give me those if I am not drinking, or am sipping whiskey with a water on the side. You could always ask for glass (any size) and I am sure they would not have a problem with it.

What I do have a problem with is paying $6 for a good beer and having it come in a flimsy solo cup.

I'm sure if you tip them a fiver with your request they will serve your tap water in the finest crystal.
Oh good, I have now transformed this into another tipping thread

Freebie branded glasses I might understand (and indeed, have a stack of reusable coke plastic glasses that I use for children's drinks when we have bbqs) but these are non branded, purchased 'beakers'.

The ice machine should NEVER have glasses in it (plastic or glass), there should be a scoop, so I am not buying that one (unless the bartenders are lazy).

In terms of the 17 year old argument, some poeple ask for their drinks in plastic glasses even when boozy (e.g. if they want to take their drink outside, some bars only allow plastic outside), so that isn't a fail safe (I have a friend who is the polar opposite of me, and only drinks from plastic, regardless of the liquid!)