Why isn't a thread_local variable destroyed when the thread returns?

Question

For a better understanding of this question, here is the code:

// code 1
#include <iostream>
#include <thread>

struct tls_test {
    tls_test()
    { std::cout << "tls_test ctor\n"; }

    ~tls_test()
    { std::cout << "tls_test dtor\n"; }

    void print() const
    { std::cout << "tls_test print\n"; }
};

thread_local tls_test t;

void thread_1()
{
    std::cout << "thread_1 started\n";
    t.print();
    std::cout << "thread_1 return\n";
}

int main()
{
    std::thread trd{ thread_1 };
    trd.join();
    std::cout << "main return\n";
}

I'm using TDM-GCC and windows 10 to test this program. here is the output:

thread_1 started
tls_test ctor
tls_test print
thread_1 return
main return

According to basic.stc.thread, the variable t is constructed, shall be destroyed on thread exit. so I think that thread is not exit even the function thread_1 returns.

Does this behavior meet the standards? If so, why? When does the thread exit?

I also read thread.threads, but seems like the standard does not explain this.