Why did the plane turn back because of the weather, instead of landing nearby?

As a baby who lives in northern Anhui but goes to school in Guangdong, there is always a special price for air tickets to the airport near her home, which is cheaper than high-speed rail tickets and almost the same as train tickets. So I basically choose to fly home. After all, anxious to return is at the end of each semester, so I certainly don't want to be slow if I can be fast. So I began to care about some knowledge about aircraft navigation.

First of all, there are generally the following kinds of weather that can affect the landing of aircraft: visibility, low-level clouds, thunderstorm areas and strong crosswinds. These don't need to be explained, and everyone should understand them. But why can't we land at a nearby airport and have to return?

First, airports are divided into various levels, and some of the larger planes fly to large airports of Hongqiao level, so they can't land at lower-level airports nearby.

another important thing is that we all know that there is a tower in the airport, and the take-off and landing of aircraft are managed by the tower. The entry and exit of each plane is planned. Many times, the plane is ready for registration, just waiting in front of the runway and not taking off because it is not its turn to take off. After all, take off and land first. And the landing of the plane doesn't mean that you can land safely. You have to go out when you get off the plane, right? Do you want to take your luggage? The plane that landed will take off again, right? You have to arrange the crew, right? This will bring an extra burden to a busy airport. One and two are fine. But what if everyone does? All the planes flying to Hongqiao have landed at Pudong Airport, which has such a large capacity and so many aprons. What about the plane in Pudong? This is just a matter of two airports. There are so many airports in China. If so, it would have been out of order. This is the entry and exit information of Shanghai Hongqiao Airport at 12 o'clock this evening.

so the landing of the plane is not that simple. Everyone would have implemented it if they could, wouldn't they? However, special air conditions such as major failures or terrorist activities can land nearby.

The above is my personal opinion. Please correct me if there are any mistakes.