Not an invention, just a fact. Are you a lawyer? What do you know about pledges?
Why haven’t you shown us the pledge(s)?
pledge (plej)
noun
the condition of being given or held as security for 1. a contract, payment, etc. a thing held in pledge
2. a person or thing given or held as security for the performance of a contract, as a guarantee of faith, etc.; something pawned; hostage
3. a token or earnest
4. a drinking to someone’s health to express good will or allegiance; toast
5. a promise or agreement
http://www.yourdictionary.com/pledge
My guess is that they either don't exist or don't say what the left wants them to.
"Let me know if I can help" is something I say to people I don't even like, it is polite conversation.