I think this is also a big part of the problem.I've seen them a few times but overlooked their last gig primarily down to the price.
There used to be a time I would check out new bands regularly at shows. For £10 you could see a B level band at the Hammy Odeon, sometimes two or three a week. The car park there was free so I could just run up there in 30 mins, park and see the band and be home before midnight. I did this all the time for years, once 5 shows in one week! I would just go up there and see what new shows had gone on sale and buy a ticket for any rock band that played. I saw many bands I would never now buy a ticket to see, some great, some not so much, but it was easy and affordable to do that at the time.
Now it's £30+ a ticket, plus £10 for parking and endless traffic jams to get there.
If a band plays Wembley it's £40-50 at least plus £20 for parking and endless traffic etc, or just a little less to go by train (with the added inconvenience). Plus I find that, and this is just my issue, if I can`t get a tickets pretty close to the stage I get kinda bored at many shows. I watched about 10 minutes of Crue (poss not the best example) at one of the shows last year from the back of the room and it was boring!
For the A list (AC/DC, Stones, Maiden etc) it becomes silly. £100 for a half decent ticket before you even take in travel expenses. For me, many bands have simply priced themselves out of my price range, plus I know I will be able to see most of the show on YouTube, often in professional quality, or later the DVD.
This years Stone Free Festival is going to cost a fortune just to see Alice. £80 before you leave the house, £21 parking and the venue is a HUGE horrible aircraft hanger. It *could* turn out to be a cool thing with the extra events they are putting on but I have my doubts. I wouldn`t pay to see Darkness or Black Stone Cherry (unless they played locally at a club maybe) so it's basically just Alice which is just about the only artist I would consider paying such money for, especially for show that is about 45 mins from where I live (but will probably be closer to 2 hours+ to get to).
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Regarding the current state of "rock" music I actually think part of the problem is the sheer number of bands out there. Back in the seventies it seems there were far fewer bands fighting for your attention and they all sounded fairly unique. You knew it was them when you heard them. Nowadays there are so many bands that sound essentially the same, they struggle to stand out from the crowd and especially struggle to compete with the greats from the past. This isn`t their fault as such, it's just the way it is.
I can happy spend an evening on YouTube jumping from unknown (to me) band to band using the automatic recommendations and enjoy the music but it's forgotten 10 minutes later. So much of it just doesn`t stand out enough to engage the listener and create a long term relationship.
For example, I'm an old school thrash fan and there are a TON of really excellent bands out there playing that style very very well, but they all sound very similar. It's like they have all distilled the essential essence of the original bands down to a formula that actually loses the very things that made those bands unique and distinct from each other. The musicianship is all of the highest caliber but there's no "soul". It's music by numbers. It's the same for "classic Rock' bands, Prog bands etc. 1000s of bands who just can`t find that essential element that makes a truly great band.
So in the end I find myself going for what I know. The classic bands or artists related to them. Occasionally something new will strike a cord with me and that is great when it happens but it doesn`t happen that much nowadays, and when I look to see where they are playing the price and hassle of getting there and back, probably on my own, puts me off.