Looks like the A3 only runs hourly to the airport from Shipley at :20 past the hour - every day of the week (incl weekends).
Bristol Airport is similar to LBA with the airport on a remote hill well outside of the city, and in June it posted record numbers of travellers using the Bristol airport bus services - over 100,000 in the month. This included 20,000 staff trips (as they’ve made it free to use for staff). So clearly using the bus hasn’t fallen out of favour as the numbers using the services are up by a fifth in comparison to last year.
In the larger urban areas, not everyone has their own car, or if they do, wants to then pay for parking or getting a taxi all the way out to the airport - so a good bus service is key, and the better it is, the more people tend to use it. The main bus service from Bristol to the airport runs 24/7 and at peak times, every 12 minutes. LBA shouldn’t be cutting services or shortening the operating times, they need to be doing the opposite. I’m sure the more money LBA is willing to invest, the better the services, and the more people will use the bus?