The short answer
In most Texas resale transactions, the seller pays for the buyer's owner policy of title insurance. But that's custom, not law — the actual contract language leaves it as an open choice.
Where it lives in the contract
TREC Form 20-19, the One to Four Family Residential Contract (Resale), addresses this in Paragraph 6A, "Title Policy": "Seller shall furnish to Buyer at ☐ Seller's ☐ Buyer's expense an owner policy of title insurance (Title Policy)…" Whoever drafts the contract checks one box or the other before the parties sign. If the box is left blank, the contract doesn't default to either party — it's an unresolved term that should get cleared up before execution, not assumed.
A common mix-up: Paragraph 6B is a different provision entirely — it's the "Commitment" clause, which gives the seller 20 days after the title company receives the contract to furnish Buyer a title commitment and (at Buyer's expense) copies of the exception documents. It has nothing to do with who pays the title policy premium. That's 6A.
Why the seller usually pays
Longstanding custom in the large majority of Texas markets is for the seller to pay for the buyer's owner's title policy, on the theory that it's part of the seller's cost of clearing and conveying good title. It shows up often enough as the default assumption that some agents treat it as a rule — it isn't. It's a negotiated term like any other, and either party can propose shifting it, particularly in a buyer's market or a distressed sale.
Owner's policy vs. lender's policy
Don't confuse the two policies in play on a financed deal. The owner's policy (Paragraph 6A) protects the buyer's equity and is the one this custom is about. The lender's title policy is a separate policy protecting the lender's lien, and it's listed as a Buyer's Expense under Paragraph 12A(2) of the same contract — the buyer pays for that one regardless of what's checked in 6A, because it's the buyer's lender requiring it.
No statute controls the allocation
Neither the Texas Property Code nor the Texas Insurance Code (which regulates title insurance rates and forms through the Texas Department of Insurance) dictates who pays the owner's title policy premium in a residential resale. TREC's role is limited to promulgating the standard contract form and its blank-and-checkbox structure — it doesn't mandate an outcome. The rate itself is a promulgated, state-set premium regardless of who pays it; what's negotiable is only who writes the check.
This is a general explanation of standard TREC contract language and common practice, not legal advice on a specific transaction. A specific contract negotiation or dispute should go to a licensed Texas real estate attorney.