pygame doesnt dedect collision between sprite and image code example

Example: pygame doesnt dedect collision between sprite and image

import sys
import pygame as pg
from pygame.math import Vector2


class Background_Line(pg.sprite.Sprite):

    def __init__(self, width, height, posX, posY, side):
        super().__init__()
        self.image = pg.Surface([width, height])
        self.image.fill((200, 30, 30))
        self.rect = self.image.get_rect(topleft=(posX, posY))
        self.side = side


class Player(pg.sprite.Sprite):

    def __init__(self, pos, *groups):
        super().__init__(*groups)
        self.image = pg.Surface((30, 50))
        self.image.fill(pg.Color('steelblue2'))
        self.rect = self.image.get_rect(center=pos)


def main():
    screen = pg.display.set_mode((640, 480))
    clock = pg.time.Clock()

    all_sprites = pg.sprite.Group()
    player = Player((100, 300), all_sprites)
    background = pg.sprite.Group(
        Background_Line(10, 300, 175, 50, 'left'),
        Background_Line(10, 300, 450, 50, 'right'),
        Background_Line(285, 5, 175, 350, 'base')
        )
    all_sprites.add(background)

    done = False

    while not done:
        for event in pg.event.get():
            if event.type == pg.QUIT:
                done = True
            elif event.type == pg.MOUSEMOTION:
                player.rect.center = event.pos

        all_sprites.update()
        #Answer
        collided = pg.sprite.spritecollide(player, background, False)
        for line in collided:
            print(line.side)

        screen.fill((30, 30, 30))
        all_sprites.draw(screen)

        pg.display.flip()
        clock.tick(30)


if __name__ == '__main__':
    pg.init()
    main()
    pg.quit()
    sys.exit()