That's a great question, and the answer is a resounding... Maybe.
There are a few things to consider when making that decision. But first, lets look at an unrelated question like: “Should I see a doctor?”
Obviously, if there's some apparent problem with our health, we should see a professional as soon as possible. Additionally, we know that it's not always prudent to wait for a problem to develop before seeking help. For example, we know that waiting for a toothache to occur will ultimately be more expensive and painful than having regular checkups. For reasons like this, we often have routine checkups even when everything seems fine.
Similar situations can occur with real estate. In some cases, problems can be very apparent. It might be obvious if water is running toward a building rather than away, or if a fence is built in the wrong place. But many times, problems are not apparent at all. This is especially true with larger or older properties. Sometimes it's virtually impossible to know for certain where a boundary is, and therefore, whether certain features (trees, fences, wells, etc) are on a certain lot. Typically we rely on word of mouth, which unfortunately become less and less reliable over time. An owner may “know” something to be true because they were told by the previous owner, who may have heard from the previous owner, who may have heard from someone who made a wild guess.
Even when boundaries are clearly physically marked, there are likely to be encumbrances of some sort. These could be written easements granting property rights to someone else (access or utility easements, for example) or some other type of exception (mineral rights are often excepted). Unfortunately, these easements are often difficult to interpret. Additionally, there could be unwritten claims to property rights by another party. A common example is a “prescriptive” easement, often in the form of an access road crossing one property to reach another. While an easement like this (if known) could easily be handled with a “handshake” agreement between cooperative owners, a permanent solution (especially in the case of a dispute) would require a surveyor and a real estate attorney.
With these ideas in mind, it would seem prudent to have a survey performed any time a buyer has any doubt about the location of a property boundary, or whether easements will have an impact on them. After all, real estate is the largest investment that most of us will make in our lifetimes. It seems logical to consult with professionals as needed so that all aspects of the purchase are well understood.
Furthermore, it may be beneficial for a seller to have a survey performed. For example, it may be possible that there's adequate space available for an Accessory Dwelling Unit, garage, or some other type of improvement. Demonstrating that options like these are possible may increase the value of the property. Additionally, simply having a survey will likely increase a potential buyer's confidence level.
In summary: Real estate is expensive. It is prudent for an owner to understand and protect their property rights, and for a buyer to perform adequate due diligence prior to purchasing. Do you need a survey before purchasing? That's up to you and depends on your situation and your willingness to accept potential risk.
PLEASE NOTE: I am not a realtor. I recommend that buyers and sellers consult with their agent before making decisions related to a purchase or sale.
Thank you for reading, and I hope this was helpful. As always, feel free to reach out with any questions you may have.