It's also the ease of it. I travelled to Indonesia a while back thinking I could pick up a SIM card once there. I didn't realise you have to register the phone itself for tax reasons (?) to white list the IMEI of the phone before buying a SIM card. It was loads easier just to buy a roaming eSIM after I arrived. In hind sight I probably could have got a better package had I shopped before hand but it got me out of a tricky situation.