That's the way ADSL has been designed. The A in ADSL stands for asymmetric. The average consumer is far more likely to be downloading stuff than uploading it to a remote server so the bandwidth available has been split to favour the download.
Consider that your total bandwidth available is approximately the sum of your download speed plus your upload speed. Now halve that and you'll see that a symmetrical connection would take much longer to download things.
Edited by caffn8me (Sat 24-Mar-18 13:04:19)