Besides being able to eat and/or drink in the auditorium, what I've noticed this year more than most and certainly different from 1978 are:
Prominence of advertisements to parents that there are spaces in the house to which they can bring children when they are crying or squirmy, but still see the performance via video. Many houses had them for a long time, but you used to have to check the fine print, or the house etiquette page. (Or learn about it from an usher or another parent.) Case in point, Texas Ballet Theater, from the link above:
Have an antsy little one? TBT values our families and is committed to offering
a welcoming, positive experience at our performances. Give your youngsters the
space to wiggle and giggle or just take a break. And to make sure you don’t miss
a step, watch the action live via windows or a television.
Should you wish to take advantage of this quiet space, you can find it here: Winspear – In the broadcast Booth on the 3rd level
Bass Performance Hall – On the west side of the 5th floor
Performances for kids on the autism spectrum. Example: Houston Ballet has two performances in the 2017-18 season:
https://www.houstonballet.org/about/ece/autism-friendly-performances/