Sachin and Lara owe those averages in the 90s to scoring big vs the lesser attacks. Fact. The better attacks in that era would be Aus, WI, Pak and Rsa. But you can't just leave it there. Rsa with any two of Donald/Pollock/DeVilliers, Pak:the Ws, WI: Curtly and Walsh, Australia : McWarne. Those were the truly great attacks.
As an example people would look at Sachin's record in the 90s vs Australia and conclude yeah he dominated their great attacks. False, he faced McWarne in 3 series and did ok and well in 2 and failed in the other. He made runs in the '97 series with McGrath absent and again in 2004 (I believe) when again McGrath was a no show.
Tendulkar: 1990s vs AUS, WI, PAK & SA
Vs AUS
1991/92 in Australia: 9 innings, 1 not out, 368 runs @ 46.00
1996 in India: 2 innings, 0 not outs: 10 runs @ 5.00
1998 in India: 5 innings, 1 not out: 446 runs @111.50
1999 in Australia: 4 innings, 0 not outs: 229 runs @ 57.25
Total: 20 innings, 2 not outs: 1053 runs @ 58.50
Vs WI
1994 in India: 6 innings, 0 not outs: 402 runs @ 67.00
1997 in West Indies: 6 innings, 1 not out: 289 runs @ 57.80
Total: 12 innings, 1 not out: 691 runs @ 62.81
Vs PAK
1999 in India (Asian Championship): 2 innings, 0 not outs: 9 runs @ 4.50
1999 in India: 4 innings, 0 not outs: 171 runs @ 42.75
Total: 6 innings, 0 not outs: 180 runs @ 30.00
Vs SA
1992-93 in South Africa: 6 innings, 0 not outs: 202 runs @ 33.67
1996 in India: 6 innings, 0 not outs: 166 runs @ 27.67
1996-97 in South Africa: 6 innings, 0 not outs: 241 runs @ 40.17
Total: 18 innings, 0 not outs: 609 runs @ 33.83
Total against AUS, WI, PAK & SA: 56 innings, 3 not outs: 2533 runs @ 47.79
Lara: 1990s vs AUS, PAK & SA
Vs AUS
1992-93 in Australia: 8 innings, 0 not outs: 466 runs @ 58.25
1995 in West Indies: 7 innings, 1 not out: 308 runs @ 44.00
1996-97 in Australia: 9 innings, 0 not outs: 296 runs @ 32.89
1999 in West Indies: 7 innings, 1 not out: 546 runs @ 91.00
Total: 31 innings, 2 not outs: 1616 runs @ 55.72
Vs PAK
1990 in Pakistan: 2 innings, 0 not outs: 49 runs @ 24.50
1993 in West Indies: 5 innings, 0 not outs: 216 runs @ 43.20
1997 in Pakistan: 6 innings, 0 not outs: 129 runs @ 21.50
Total: 13 innings: 0 not outs: 394 runs @ 30.30
Vs SA
1992 in West Indies: 2 innings, 0 not outs: 81 runs @ 40.50
1998-99 in South Africa: 10 innings, 0 not outs, 310 runs @ 31.00
Total: 12 innings, 0 not outs, 391 runs @ 32.58
Total against AUS, PAK & SA: 56 innings, 2 not outs: 2401 runs @ 44.46
So both Tendulkar and Lara still had pretty good averages overall against the very very strong bowling attacks in the 1990s - AUS, WI, PAK & SA