Detained by a door

We went to a lovely restaurant one night, and during the evening, I excused myself to go to the bathroom. As I approached the "Ladies" a young woman held the door open for me as I entered.  She was quick and nimble, in and out like a flash, leaving me struggling with button and zip, taking an awfully long time. After washing my hands, I went to open the door but found I could not. The door was so incredibly heavy, I was unable to pull it open. I stood there a moment wondering what to do.  Should I use my mobile phone to call my husband who was sitting a few meters from where I was being held prisoner by an unruly hefty door that refused to budge? I felt utterly ridiculous so I decided to wait till another woman came in and hopefully would hold the door open for me so that I could escape. After a few minutes had gone by, and no one had appeared, I began to wonder how long I would have to be absent until someone at the table realised I was still in the bathroom. Finally, much to my relief, a woman flung the door open and relieved I stepped forward whilst she held the door back for me. For the life of me, I cannot fathom why they would make a bathroom door so very heavy, and I cannot think of a logical reason. I can understand the front door of premises requires to be heavy, but a bathroom door? This is not the first restaurant that I have come across this problem, and clearly whoever is designing bathroom doors in public places doesn't take into consideration, the elderly, disabled, pregnant ladies, or small children. There needs to be far greater awareness when it comes to customer comfort, whether it be putting a chair in the changing cubicle of a clothing shop, or making sure the door to the toilet doesn't weigh half a ton. Could this be the illusive answer as to why women often go to the bathroom in pairs?