require that X be used VS. require X to be used

Question

Some cities have a rule requiring that a certain percentage of the budget be used to fund public art.

I am wondering the reason for being omitted the preposition to before used to.

Answer 1

Some cities have a rule requiring that a certain percentage of the budget be used to fund public art.

The clause beginning with "requiring" employs the subjunctive mood, more precisely, the so-called mandative subjunctive:

I require that the budget be used to fund public art.
We asked that it be done yesterday.

Mandative subjunctive uses the "bare infinitive", the basic form of the verb without the particle to.

The mandative (or "present") subjunctive expresses a circumstance that is desired, demanded, recommended, necessary, etc.

If you spot a verb like insist, suggest, demand, prefer, an adjective like necessary, desirable, or a noun like recommendation, necessity, and after (or subordinate to) it, a that-clause, it's a good sign you have a mandative subjunctive.

Answer 2

The reason for the "missing to" is the fact that here not infinitive, but subjunctive is used:

Quote from Wikipedia, emphasized by me:

The main use of the English present subjunctive, called the mandative or jussive subjunctive,(1) occurs in that clauses (declarative content clauses; the word that is sometimes omitted in informal and conversational usage) **** Such a clause may be dependent on verbs like insist, suggest, demand, prefer,(2) adjectives like necessary, desirable,(3) or nouns like recommendation, necessity;(4) it may be part of the expression in order that... (or some formal uses of so that...); it may also stand independently as the subject of a clause or as a predicative expression.

In short: as it's a mandatory requirement, it is stated using subjunctive instead of indicative.

Answer 3

The use of "be used" instead of "to be used" is grammatically correct in the sentence. No doubt, the sujunctive mood is mostly found in conditional if-clauses, but it also expresses a wish, suggestion, command, or state of necessity. The present subjunctive of "to be" is "be" for all persons and for all other verbs it's bare infinitive and there is no addition of "s" to the infinitive for the third person singular.

According to this rule of grammar, we cannot use "to be" in the sentence. Instead, we use only "be". Please look at the following sentences in the subjunctive mood:

It's important that he attend the meeting. (we cannot use attends)

It's necessary that all matters be considered. (we cannot use to be)

By the way, it is OK in BE if we say "it's important that he should attend the meeting" and "it's necessary that all matters should be considered".