Why is there no Air Con on UK Public Transport?

Why are British buses and trains so ill equipped for hot weather? One would think their proprietors had never experienced a sunny day in their lives. This year, temperatures are soaring, and with global warming it’s possible next year will be even worse. Where, then, is the air conditioning? That cooling blast that can save us from so much terrible suffering? London’s public transport is the most expensive in the world, so some of those profits should surely be used towards making sure we're not fainting from heat in the summer? Trying to fan oneself with a magazine, or distracting oneself by playing Pixel Art - Color by Number, or checking social media, are hardly enough to stop the sweltering heat from affecting one. What are your thoughts on this? I for one would like UK transport bosses to be held more accountable, and think the government should act on this.