...is filmed before a live studio audience

Just had a discussion with one of my mates, about old American Television Sitcoms, and we remembered all the way up to about the early nineties, an announcement was made after the title sequence, on every episode:

"Happy Days is filmed in front of a live studio audience."
"Cheers is filmed in front of a live studio audience."
"The Cosby Show is filmed in front of a live studio audience." and so on...

What was the purpose of this? Does anyone have any clue? We can't think of any substantial reason for them to religiously announce that a studio audience was present for the recording. Can anyone shed any light on this?

Possibly regulatory, like gameshows have to put in the credits that they have been edited and that contestants have been briefed on the game rules.

Would have thought it was to highlight that the laughter wasn't canned - so many comedies/shows played in taped laughter or added it later.

For the first few series of Cheers, the now iconic voiceover wasn't made, instead the line 'FILMED BEFORE A LIVE STUDIO AUDIENCE' was inserted onto the copyright page of the credits, in a 'blink and you'll miss it' kind of way. Similar things seemed to happen to a lot of big 80's US sitcoms.

Was the way in which the acknowledgement was made more prominent later in the 80's the result of regulatory stipulation, or was it just seen as a selling point for the big network sitcoms which used live audience as opposed to the cheaper syndicated stuff which used canned laughter?