Towers wouldn't necessarily need the most up to date technology though. Their architectural lighting they use for Scarefest and Fireworks are vastly just coloured flood and wash lights, and there's really no need for them to do much more than that. As long as it's highly IP rated (resistant against water and dust) then they could bulk buy and keep permanently installed. However, it is much cheaper to hire lights than it is to buy outright, so I can see why they'd not opt to do so. A fairly standard theatrical moving profile light could cost upwards of £7k. To hire for a few weeks - a mere fraction of that.