Great question—and a very practical one. The answer depends heavily on where you're buying the bench and what grade it is.
For most commercial-grade park benches (the kind you'd see in public parks, campuses, or municipal areas), anti-theft hardware is almost always included. This typically means tamper-proof screws, security bolts, or anchor plates designed to require special tools for removal. Many manufacturers understand that theft and vandalism are real concerns in public spaces, so they specifically design their benches with security in mind.
However, if you're buying a residential or budget-grade bench from a big-box store or online marketplace, the situation is often different. Those benches frequently come with standard Phillips-head or hex bolts that are easy to steal. In that case, you're better off buying a separate anti-theft hardware kit, which is widely available at hardware stores or online. These kits usually contain special one-way screws, tamper-resistant socket heads, or heavy-duty locking brackets.
Also, keep in mind that even if the bench comes with security hardware, some installation scenarios—like concrete anchoring—may require additional bolts or expansion anchors that aren't in the box. In short: always check the product description or ask the seller directly. If it's a commercial bench from a reputable manufacturer, you're probably covered. If it's a cheaper model, plan to spend an extra $10–$30 on theft prevention.
My personal tip? Even if the hardware is included, upgrade to a stainless steel tamper-proof kit if you can. Rust can make security bolts harder to remove over time, which ironically looks like a security feature but becomes a maintenance headache. Choose wisely, and your bench will stay where you put it.