Why does django ORM retrieve the same related object multiple times when the foreign key is the same?

Given the following code:

class Customer(models.Model):
    name = models.CharField(max_length=30)

class Project(models.Model):
    name = models.CharField(max_length=30)

for p in Project.objects.all():
   print (p.name, p.customer.name)

I then create the following objects:

customer 1
  project 1
  project 2
  project 3
customer 2
  project 1
  project 2
  project 3

The for loop prints the result is as expected:

Project 1 Customer 1
Project 2 Customer 1
Project 3 Customer 1
Project 4 Customer 2
Project 5 Customer 2
Project 6 Customer 2

By checking the connection.queries, I see that django has executed 7 queries:

'SELECT "myapp_project"."id", "myapp_project"."customer_id", "myapp_project"."name", "myapp_project"."is_active" FROM "myapp_project"'
'SELECT "myapp_customer"."id", "myapp_customer"."name", "myapp_customer"."is_active" FROM "myapp_customer" WHERE "myapp_customer"."id" = 1 LIMIT 21'
'SELECT "myapp_customer"."id", "myapp_customer"."name", "myapp_customer"."is_active" FROM "myapp_customer" WHERE "myapp_customer"."id" = 1 LIMIT 21'
'SELECT "myapp_customer"."id", "myapp_customer"."name", "myapp_customer"."is_active" FROM "myapp_customer" WHERE "myapp_customer"."id" = 1 LIMIT 21'
'SELECT "myapp_customer"."id", "myapp_customer"."name", "myapp_customer"."is_active" FROM "myapp_customer" WHERE "myapp_customer"."id" = 2 LIMIT 21'
'SELECT "myapp_customer"."id", "myapp_customer"."name", "myapp_customer"."is_active" FROM "myapp_customer" WHERE "myapp_customer"."id" = 2 LIMIT 21'
'SELECT "myapp_customer"."id", "myapp_customer"."name", "myapp_customer"."is_active" FROM "myapp_customer" WHERE "myapp_customer"."id" = 2 LIMIT 21

But my question is, why does the django ORM repeat the same query 3 times to retrieve the customer 1 associated with the projects 1, 2 and 3? I thought that the Customer data would be stored in the cache, and only 3 queries would be executed in total, like this:

'SELECT "myapp_project"."id", "myapp_project"."customer_id", "myapp_project"."name", "myapp_project"."is_active" FROM "myapp_project"'
'SELECT "myapp_customer"."id", "myapp_customer"."name", "myapp_customer"."is_active" FROM "myapp_customer" WHERE "myapp_customer"."id" = 1 LIMIT 21'
'SELECT "myapp_customer"."id", "myapp_customer"."name", "myapp_customer"."is_active" FROM "myapp_customer" WHERE "myapp_customer"."id" = 2 LIMIT 21'

I would bet that this is by design. What is the rationale behind this behavior?

Thanks

(PS: I know that could have used select_related and use only one query joining the two entities, but this is more of a conceptual question):

Project.objects.select_related('customer')