When LAX-LAS TED was mainline (ie, before TED started), booze was offered on the 44-54minute flight, so not sure why it's not on TED. I do think it's hit/miss now. None on my RT last mth. wingless got it to LAS but not from LAS a week or so ago.
So who knows the rationale for when it is/isn't as the timeframe is relatively the same. On longer flights I think booze no problem. Just keep a drink cert w/ you in case you do want a 'quick' one on the LAX-LAS flights & by luck they offer it.
PS - I'd much rather slam down a quick one than drink the disgusting Crystal Light lemonade (that looks actually green like Gatorade). But I can do w/o anything for 45-50 if I need to.