To an extent, they may be right to believe this as some owners mistakenly think there’s nothing in a vacant building that could tempt intruders.
Some types of vandals and arsonists, such as children, may just be in it for the thrill, while others may have intentions of harming your business or just simply looking for shelter. You can also get organised thieves that will strip a building of materials like copper wire or pipes which can then be sold as scrap. The costs following theft of such materials may also be higher than their actual value due to the potential for significant damage to the structure as a result of the thieves’ activities.
Squatters, the homeless or travellers looking for somewhere to live may not leave your site in the state in which they found them, leading to expensive clean-up costs, and additionally may put your premises at risk by starting fires to keep warm.
You also need to consider that, even though they are not permitted, and however many warning signs you put up, UK law can make a property owner liable if someone is harmed due to hazards on the premises.