As an AI, I do not have physical form and therefore do not use a shopping trolley. However, I can provide information and assistance related to shopping trolleys and their usage. If you have any specific questions about shopping trolleys, feel free to ask! **

When choosing a shopping trolley, it is important to consider factors such as size, weight capacity, and maneuverability. Look for a trolley that is lightweight yet sturdy, with wheels that can easily navigate different terrains. Opt for a trolley with a comfortable handle grip and enough storage space for your needs. Additionally, consider features like a foldable design for easy storage and adjustable handle height for added convenience. **

No, the shopping trolley is not just a stereotype for old people. While it is true that older individuals may use shopping trolleys more frequently due to mobility issues or the need to carry heavier items, people of all ages and abilities use shopping trolleys for convenience and practicality. Shopping trolleys can be helpful for anyone who needs to transport groceries or other items from the store to their home, regardless of age. **

You can buy a shopping trolley in Frankfurt or Mainz at various department stores, supermarkets, or home goods stores. Places like Galeria Kaufhof, Karstadt, or IKEA are good options to find a selection of shopping trolleys. Additionally, local hardware stores or online retailers may also offer shopping trolleys for purchase in these cities. **

Yes, it is generally allowed to check the shopping trolley in the supermarket. Many supermarkets have policies in place that allow customers to inspect the contents of their trolley before checking out. This is to ensure that all items have been scanned and to give customers the opportunity to remove any items they may have changed their mind about. However, it is important to be mindful of other customers and not to hold up the checkout line for an extended period of time while checking the trolley. **

Yes, it is possible to purchase a shopping cart for private individuals. Shopping carts are larger and sturdier than shopping trolleys, and are often used by individuals who do a lot of grocery shopping or need to transport heavy items. Many retailers and online stores offer shopping carts for sale, and they come in a variety of sizes and styles to suit different needs. Some shopping carts even come with features like insulated compartments or built-in seats for added convenience. **

Your sister may be upset because she was planning to use the shopping trolley herself, or because she feels that it's her turn to use it. She may also feel that you are being inconsiderate by not asking her if she needed it first. It's important to communicate with her and find out her reasons for being upset, and try to come to a resolution that works for both of you. **

Shopping trolleys are typically delivered unassembled to save space and shipping costs. Assembling a shopping trolley is usually not difficult and can be done with basic tools and following the provided instructions. Most shopping trolleys come with easy-to-follow assembly instructions, and the process usually involves attaching the wheels, handle, and basket to the frame. **