Or might it be because they don't bother to marry in the first place? No marriage--No divorce.
Reminds me a bit of a scene from the great Gershwin opera
Porgy and Bess. A fake lawyer offers to sell Bess a divorce from Crown, so that she can be with Porgy. But Bess was never married to Crown.
FRAZIER: Ah ha, ah ha, Porgy's Bess, eh? Den I guess she'll be wantin' divorce.
PORGY: Huh?
FRAZIER: Ef de woman livin' wid you now, she got to have divorce from Crown or else it ain't legal.
(Takes document and shows it to Porgy)
PORGY: How much dat t'ing cost?
FRAZIER: One dollar. Dat is, if there ain' no complication.
PORGY: Bess, you likes to have divorce?
BESS: What you think, Porgy?
PORGY: I'm agoin' to buy you a divorce.
(Hands Frazier money)
FRAZIER: Wait a minute, it ain't legal yet. Yo' name?
ALL: Bess!
FRAZIER: Yo' age?
BESS: Twenty year.
ALL: Lord, Lord, listen what she say. Dat girl's thirty if she's a day!
FRAZIER: You desire to be divorce from dat man Crown?
ALL: Sho' she do, sho' she do, Yes suh, yes suh, sho' she do!
FRAZIER: I'm askin' you.
BESS: Yes, boss, dat's true.
FRAZIER: Address the court a "Yo' honor."
ALL: Yes, yo' honor. Yes, yo' honor.
FRAZIER: When was you an' Crown marry?
BESS: I don't rightly remember, yo' honor.
FRAZIER: One yeah, five yeah, ten yeah, what?
LILY: Dat gal ain' never marry!
FRAZIER: Ah, dat's a complication!
ALL: Dat's a complication. Dat's a complication, Lord, Lord --
MARIA: Dat is a complication.
PORGY: You can't sell her divorce, gimme back my dollah!
(Everybody laughs)
FRAZIER: 'Course I sells divorce. You got no right to laugh, but it take expert to divorce woman what ain't marry, an' it cos' you, ahem, a dollar an' a half.
BESS: Don't pay him, Porgy. Don't let him take you in.
FRAZIER: All right, go on livin' in sin.
(Porgy counts out money and gives it to Frazier,
who signs and seals paper and hands it to Bess)
Good day to you, Missis Porgy. Only dollar an' a half to change from woman to lady.