The customer service agent treated his customer non-chalantly.

  1. Many storekeeper are lax in their duty when it comes to selling tobacco product.They don’t check the ID of the buyers.It has become a concern of the society.
  2. The employee of the shop are lax in performing their job.
  3. The customer service agent treated his customer non-chalantly/aloofly.
  4. He treats his customer with care free attitude, inattentive and unfriendly.

Are the sentences above correct? Please let me know.

  1. Many storekeeper are lax in their duty when it comes to selling tobacco product. They don’t check a buyer’s ID. It has become a concern for society.
  2. The employees of the shop are lax in performing their jobs.
  3. The customer service agent treated his customer(s) nonchalantly/ in an aloof manner.
  4. He treats his customers with a carefree attitude, and is inattentive and unfriendly. (I would not say ‘carefree’ was the word you needed here. ‘Careless’ would be more appropriate!)