From the website: https://www.gonortheast.co.uk/bus-driver
"This takes the basic annual wage for Go North East bus drivers on a guaranteed 39 hour week to £22,308 in the first year and £26,019 after year one (or straight away for existing licence holders) with regular opportunities to earn overtime each week on top of this."

So whilst the 30k is quoted in the image, the representative examples are between £22,308 and £26,019, with it later suggesting that "it's not uncommon for drivers to earn around £35,000 a year!"

Averaging exactly 45 hours a week at £12.83 per hour would be just over £30,000 a year.
Averaging exactly 52.5 hours a week at £12.83 per hour would be just over £35,000 a year.

Without commenting on the advert itself, there's too many variations of what the rate of pay is, with the headline figures not looking so attractive after you work out the overtime you'd have to sustain. It's also worth remembering that as with all overtime, it can be taken away as easily as it is given out, and from a financial sense, it's not a great idea to become reliant on variable pay.

If a role isn't salaried, then it should be quoted as an hourly rate.