[shabble]

There seem to be 2 confused issues in this (sub)thread.

Firstly, the Therapeutic Index argument (ratio of effective dose to dangerous/fatal dose), for which the 2 drugs are (very) roughly equivalent, based on some back-of-envelope estimates (~10:1 for EtOH, 14:1 - 3:1 for GHB).

The second is the 'commonly encountered form' argument, which I think was your main point, and appears to be misunderstood. Alcohol, with the benefits of being legal and easily available, is available in known purity solutions anywhere from 1~90%.

The biggest problem (AFAIK) with things like GHB in a bar/club environment is the fact it must be concentrated enough to be small enough to easily smuggle in/out. It has specific other unfortunate properties as well, like being very destructive to many types of plastic. Dosing with an eye-dropper into an existing drink is apparently quite common, and I can easily imagine this leading to accidental overdosing in a crowded/loud/intoxicated environment. You must also account for the fact that there's not nearly the same quality control in terms of purity from batch to batch, which combines badly with the low Therapeutic/Effective Index.

The other difference is, even if your bartender is serving you 180 proof rum, he's probably not going to let you chug the whole bottle of it, regardless of demand.