Most Realtors do provide virtual tours for their listings. However,some sellers prefer not to have a virtual tour of their home for privacy and security reasons. Every realtor offers different services to Sellers , but not all offer professional photos and virtual tours.
Not every home has a virtual tour because Agents don't always create them due to the time and expense of it. I have made short videos and virtual tours of homes for out of town buyers and could do the same for a small fee, for any home buyer who's interested in a particular home.