The reason why barbecue shops don't use machines to thread skewers can be explained from two aspects: ingredient list and production steps:

1. List of ingredients: Different ingredients have great differences in texture, shape and size, such as meat, vegetables and seafood. Automatic stringing machine needs certain rules and fixed methods in stringing, but it is difficult to adapt to the diversity of different ingredients, which can easily lead to broken ingredients or improper control of baking time, too ripe or too raw.

2. Production steps: The handmade skewers in the barbecue shop are made by the chef himself, which can perfectly integrate the baking time, interval time, heat and seasonal ingredients. Different ingredients have different requirements for baking time and duration. Hand-made ingredients can better grasp these key factors to achieve the best taste and quality.

To sum up, barbecue shops do not use machines to wear skewers, mainly because of the differences of different ingredients and the advantages of hand-making. Manual barbecue can better adapt to the diversity of ingredients and the requirements of baking, thus providing customers with more delicious and higher quality barbecue.