Do you remember doing A levels and whether you had a job at the time?
I did, I worked Saturdays 9-5 in a local shop. It was important to earn my own money to save for a holiday after A levels and to have some to take to Uni. It also gave me vital experience with customers (on top of previous waitressing) when I was looking for bar work in Uni.
My son had a job during A levels which was very flexible and fitted well with his hobbies, sports and revision. He cleans at the gym where he trains daily so he just stays a bit later after a workout. He did some labouring work in the Easter hols and half terms which gave him more money. He achieved the A levels he needed for the Uni course he's starting next month.
His jobs, his sports, hobbies, volunteering, and work experience were all incredibly valuable on his CV and his UCAS form.
It's good for older teens to learn the value of money, budgeting, and in those entry level jobs so they can better appreciate the roles that all sorts of people play in life.
His friends had jobs too, some worked in bars or pubs, or local sports club bars, some were lifeguards, some were tutors for younger pupils, some worked in restaurants, shops etc.
It's normal and it's all part of learning to juggle, manage their time and responsibilities, develop their customer service skills, make new friends and connections.