Why can compressed air hose reels be a leakage source?

Do all air hose reels leak?

Managing Leaks (and everything else) in an Industrial Compressed

Power Drives Inc. (@PowerDrivesPDI) / X

Retractable Pressure Hose Reel-1/4in

Troubleshooting Tips for a Leaking Air Compressor Tank - Master

Jupiter Pneumatics Hose Reel w/ Hose: 3/8 ID Hose x 75', Spring Retractable - 300 psi, 3/8 NPT Inlet, 1/4 NPT Outlet, Steel, Silver

ReelWorks 50 ft. Retractable Air-Hose Reel With Hose at Tractor

Hose Reel: What Is It? How Is It Made? Types & Usage

81075 OLP - 3/8 in. x 75 ft. Premium Duty Dual Pedestal Hose Reel